Compositions and methods for regulating arterial tone

ABSTRACT

The present invention provides compositions and methods for regulating arterial tone based on the discovery herein of novel expression and regulation of hemoglobin alpha and cytochrome B5 reductase 3 and the effects on NO and NOS.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a national stage filing of International ApplicationNo. PCT/US2013/066186, filed Oct. 22, 2013, which is entitled topriority pursuant to 35 U.S.C. 119(e) to U.S. Provisional PatentApplication Ser. No. 61/716,846, filed Oct. 22, 2012, the entiredisclosures of which are herein incorporated by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with government support under Grant Nos.HL088554, HL112904, HL059337, and HL101871, awarded by The NationalInstitutes of Health. The government has certain rights in theinvention.

BACKGROUND

Models of unregulated nitric oxide (NO) diffusion do not consistentlyaccount for the biochemistry of NO synthase (NOS)-dependent signaling inmany cell systems. For example, endothelial NOS (eNOS) controls bloodpressure, blood flow and oxygen delivery through its effect on vascularsmooth muscle tone, but the regulation of these processes is notadequately explained by simple NO diffusion from endothelium to smoothmuscle.

Control of arteriolar smooth muscle tone is central to regulation ofblood pressure, blood flow and oxygen delivery. Nitric oxide (NO)synthase (NOS) in endothelial cells helps to regulate arteriolar tone bysignaling smooth muscle relaxation across the myoendothelial junction(MEJ). However, substantial evidence suggests that simple, unregulatedNO diffusion does not account for the physiology and biochemistry ofNOS-dependent signaling.

Endothelial NOS modulates blood vessel diameter in response to bothvasodilators and vasoconstrictors. For example, it is known that duringarterial constriction NO from endothelium feeds back on smooth muscle tocontrol the magnitude of the response to a vasoconstrictor (e.g.,phenylephrine (PE)). Heme iron oxidation state affects the chemistry ofNO-hemoglobin interactions.

There is a long felt need in the art for compositions and methods forregulating the tone of reactive vessels. The present invention satisfiesthese needs.

SUMMARY OF THE INVENTION

Disclosed herein is a new paradigm in the regulation of NO signaling.The surprising result disclosed herein is that hemoglobin (Hb) α isexpressed in arterial endothelial cells (ECs) and enriched at themyoendothelial junction (MEJ), where it regulates the effects of NO onvascular reactivity. It is disclosed herein that endothelial hemoglobinα regulates NOS-dependent cell signaling across the MEJ. Specifically,hemoglobin α is 1) expressed in arteriolar endothelial cells, 2)enriched at the MEJ, 3) in complex with endothelial NOS, and 4) plays arole in the regulation of vascular tone. These effects are specific forthe α isoforms of hemoglobin and abrogated by its depletion. It is alsodisclosed herein that endothelial hemoglobin α heme in the Fe³⁺ stateenhances NOS bioactivity. Further, cytochrome B5 reductase 3 catalyzesthe reduction of Fe³⁺-state hemoglobin α in endothelial cells. Geneticand pharmacological inhibition of cytochrome B5 reductase 3 enhancesNOS-dependent arteriolar relaxation. Thus, endothelial heme oxidationregulates the tone of resistance blood vessels.

One embodiment provides an amino acid sequence comprisingLSFPTTKTYFPHFDLSHGSA (SEQ ID NO:1) and conservative amino acidsubstitutions thereof. In another embodiment, the amino acid sequencecomprises LSFPTTKTYF (SEQ ID NO:2) and conservative amino acidsubstitutions thereof. In one embodiment, the amino acid sequenceconsists of LSFPTTKTYFPHFDLSHGSA (SEQ ID NO:1) or LSFPTTKTYF (SEQ IDNO:2). Another embodiment provides a plasma membrane permeabilitysequence. In one embodiment, the plasma membrane permeability sequencecomprises an HIV-tat tag sequence of YGRKKRRQRRR (SEQ ID NO:3). Anotherembodiment provides a pharmaceutical composition comprising the aminoacid sequences described herein and a physiologically acceptablecarrier.

One embodiment provides a method to increase nitric oxide comprisingadministering to a subject in need thereof an effective amount of theamino acid sequence or pharmaceutical composition described herein, anantibody directed against Hb α, an antibody directed against SEQ ID NO:1 or 2, or an inhibitor of Hb a or CytB5R3 activity or expression so asincrease nitric oxide.

Another embodiment provides a method to inhibit or reducevasoconstriction comprising administering to a subject in need thereofan effective amount of the amino acid sequence or pharmaceuticalcomposition described herein, an antibody directed against Hb α, anantibody directed against SEQ ID NO: 1 or 2, or an inhibitor of Hb a orCytB5R3 activity or expression so as to inhibit or reducevasoconstriction.

A further embodiment provides a method to decrease blood pressurecomprising administering to a subject in need thereof an effectiveamount of the amino acid sequence or pharmaceutical compositiondescribed herein, an antibody directed against Hb α, an antibodydirected against SEQ ID NO: 1 or 2, or an inhibitor of Hb a or CytB5R3activity or expression so as to decrease blood pressure.

Another embodiment provides a method to prevent or treat a disease orcondition comprising administering to a subject in need thereof aneffective amount of the amino acid sequence or pharmaceuticalcomposition described herein, an antibody directed against Hb α, anantibody directed against SEQ ID NO: 1 or 2, or an inhibitor of Hb a orCytB5R3 activity or expression so as to prevent or treat said conditionor disease, wherein the disease or condition comprises hypertension,stroke, arteriosclerosis, hemoptysis (e.g., massive), gastrointestinalbleed, epistaxis, migraine headache (e.g., post-prodome) ormusculoskeletal injuries (e.g., those in the acute phase), trauma,hemangioma repair (and other intraoperative causes of bleeding),bleeding diatheses, uterine hemorrhage, menorrhagia, septic shock,anaphylactic shock, erectile dysfunction, musculoskeletal/sport injuries(e.g., those in repair phase), or Raynaud's.

One embodiment provides a method to regulate blood pressure comprisingadministering to a subject in need thereof an effective amount of theamino acid sequence or pharmaceutical composition described herein, anantibody directed against Hb α, an antibody directed against SEQ ID NO:1 or 2, or an inhibitor of Hb a or CytB5R3 activity or expression so asto regulate blood pressure.

Another embodiment provides a method to relax resistance arteriolescomprising administering to a subject in need thereof an effectiveamount of the amino acid sequence or pharmaceutical compositiondescribed herein, an antibody directed against Hb α, an antibodydirected against SEQ ID NO: 1 or 2, or an inhibitor of Hb a or CytB5R3activity or expression so as to relax resistance arterioles.

In one embodiment, the administration is IP or oral. One embodimentfurther comprises administering inhaled oxygen (e.g., oxygen from anoxygen tank).

In one aspect, the HB α expressed by endothelial cells controls orregulates endothelial-smooth muscle cell communication. It is alsodisclosed herein that not all endothelial cell tested express Hb α.Surprisingly, this function is unique to Hb α and is abrogated by itsgenetic depletion. Also disclosed herein is CytB5R3 regulation of theeffect of Hb α on nitric oxide bioactivity.

Mechanistically, endothelial Hb α heme iron in the Fe³⁺ state permits NOsignaling, and this signaling is shut off when Hb α is reduced to theFe²⁺ state by endothelial cytochrome B5 reductase 3 (CytB5R3). Geneticand pharmacological inhibition of CytB5R3 increases NO bioactivity insmall arteries. These data reveal a novel mechanism by which theregulation of intracellular Hb α oxidation state controls NOS signalingin non-erythroid cells. This paradigm may be relevant to heme-containingglobins in a broad range of NOS-containing somatic cells.

The present invention, based on the results disclosed herein, providescompositions and methods to regulate Hb α heme oxidation state in orderto regulate both NO diffusion and bioactivation. The present inventionfurther provides compositions and methods for regulating Hb α bymodulating its interaction with CytB5R3, the interaction in endothelialcells being a surprising result disclosed herein. Additionally, thepresent invention provides compositions and methods for causing loss ofCytB5R3 or decreased expression or activity levels to inhibit metHb αreduction. The present invention further provides compositions tostimulate CytB5R3 expression or levels or activity to enhance metHb αreduction. The compositions and methods useful for regulating CytB5R3are also useful for regulating arterial tone.

The present invention encompasses the use of compositions and methodsfor inhibiting Hb α expression, levels, or activity to inhibit arterialreactivity to a PE type of stimulus but increased reactivity to aregulator such as Ach in the arteries being targeted, unless a NOSinhibitor is also administered. The present invention therefore alsoencompasses the use of different regulators, alone or in combination.

It is disclosed herein that Hb α interacts with eNOS and compositionsand methods are provided for regulating this interaction. In one aspect,the interaction is enhanced, and in another it is inhibited. In oneaspect, the compositions and methods of the invention are useful forregulating blood vessel tone by controlling NO diffusion, based on theHb α interaction with eNOS.

The invention further encompasses compositions and methods useful forinhibiting Hb α expression, levels, or activity to stimulate or cause anincrease in NO diffusion across the vessel wall. The invention furtherencompasses the use of compositions and methods where carbon monoxideligated Fe²⁺ heme results in increased NO diffusion.

The present invention further provides compositions and methods forregulating blood vessel tone by regulating the interaction of Hb α, eNOSand CytB5R3.

The present invention provides compositions and methods for regulatingvascular reactivity and diameter of arteries. The compositions andmethods of the invention are also useful for, inter alia, regulatingblood pressure, arteriogenesis, anti-inflammatory signaling, andregulating redox signaling.

Useful compounds are disclosed herein, and others in the art can also beused to practice the invention. For example, PTU has been shown hereinto regulate endothelial CytB5R3 and to alter vascular reactivity and NOdiffusion.

In one embodiment, the composition and methods of the invention areuseful for constricting resistance arterioles. In one aspect,administration of a pharmaceutical composition comprising an effectiveamount of at least one useful molecule of the invention can be used todecrease MEJ Hb oxidation.

The compositions and methods of the invention are useful, for example,in treating massive hemoptysis, GI bleeding, epistaxis, migraineheadaches, (post-prodrome), musculoskeletal injuries in the acute phase,trauma, surgical injury, and hemangioma repair and other intraoperativecauses of excessive bleeding, bleeding diatheses, uterine hemorrhage ormenorrhagia, septic shock, and anaphylactic shock.

The present invention encompasses the use of more than one type ofmolecule to regulate an activity described herein, including, but notlimited to, drugs, DNA, RNA, oligonucleotides, antisenseoligonucleotides, siRNA, miRNA, proteins, antibodies, monoclonalantibodies, polyclonal antibodies, and fragments, derivatives, andhomologs thereof. The methods further encompass the use of more than oneof each type of molecule, alone or in combination.

The compositions and methods of the invention are also useful forincreasing MEJ and endothelial Hb α expression, NO oxidation to nitrateand thiol oxidation to dithiols with high FiO₂ and paO₂.

The present invention further provides compositions and methods usefulfor relaxing resistance arterioles, as opposed to restricting theresistance arterioles as described above. Examples of specifictherapies, compounds, and combinations include, but are not limited to,PTU or novel met reductase inhibitor, xanthine, nitroglycerine ornitrite and occupying Fe2+. This includes the use of local CO, localexcess NO, increased NO+ transferred from ironIII: local or systemic“thiol” from the group via NAC, CoA, cyteine, cysteamine, GSH,homocysteine and NO released from Fe2+, light and laser therapies, andheat. The present embodiment can be used to achieve local vasodilation,systemic arteriolar dilation, and can be used in competing technologies.

The present invention also provides for regulating the signaltransduction pathway disclosed herein by using molecules that are activein regulating various points in the pathway.

The present application provides pharmaceutical compositions comprisingat least one compound of the invention. The present invention furtherprovides for administering a pharmaceutical composition comprising aneffective amount of a compound, drug, or molecule of the invention to asubject in need thereof.

The present application further discloses methods for identifyingadditional compounds useful for practicing the invention. The methods ofthe invention further encompass the use of molecules effective topractice the invention, including molecules found to be effective usingthe assays of the invention.

The present invention includes the use of kits comprising apharmaceutical composition comprising an effective amount of a compound,drug, or molecule of the invention, an applicator, and an instructionalmaterial for the use thereof.

Various aspects and embodiments of the invention are described infurther detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1, comprising 1A1, 1A2, 1B1, 1B2, 1C1, 1C2, 1D, 1E, 1F1, 1F2, and1G, —Monomeric Hb α is expressed in ECs and enriched at the MEJ. a,Quantitative Western blot (A1) analysis for Hb α and Hb β expression incoronary EC, MEJ or SMC lysates from cells plated on Transwells orplastic (n≧4), or in fibronectin and gelatin used to coat Transwells.(A2) Red blood cells served as a positive control and GAPDH was used asloading and normalization control for quantitation (bottom left).Immunofluorescence for Hb α (red) and Hb β (green) (bottom right). b,(B1) TEM analysis of Hb α expression in TD (top) or (B2) carotid(bottom) arteries visualized using 10 nm gold beads (black particles).Arrow indicates MEJ. Graphs on the right represent Hb α localizationcalculated by measuring the number of beads per μm² (n≧7). c,Quantitative Western blot (C1) analysis for Hb α and Hb β expression inisolated TD or carotid arteries. (C2) Tubulin served as a loadingcontrol and red blood cells were used as a positive control (n≧3). d,Immunofluorescence of transverse sections from mouse carotid or TDarteries or from a human skeletal muscle arteriole. In all images, redindicates Hb α expression, green shows internal elastic laminaautofluorescence, and blue specifies nuclei. White boxes in mouse TD andcarotid artery in left panels indicate the region of interest magnifiedin the right panel. e, En face images of Hb α expression (red) and Hb β(green) expression in ECs from TD or carotid arteries. Blue stainingrepresents nuclei. f, Western blot analysis of TD artery, EC, MEJ, SMCor red blood cell lysates that were chemically crosslinked (F1) usingBS₃ to determine quaternary structure of Hb α or not cross-linked (F2).g, mRNA analysis from EC, MEJ and SMC lysates isolated from VCCC, TD andcarotid arteries. 18S was used as a normalization factor. In a, b, c,and g open bars represent in vitro data and striped bars indicate exvivo data. Scale bar in a is 2 μm, b is 0.5 μm, d indicates 30 (TDartery and carotid) or 10 (human skeletal muscle artery) μm and esignifies 10 μm. L is lumen (b, d) and n.s. indicates not significant(b, c). p values are shown for each comparison. All error bars represents.e.m.

FIG. 2—Hb α regulates vessel tone, NO diffusion and associates witheNOS. a, Time course to 50 μM PE, b dose response to PE and c doseresponse to Ach on TD arteries treated with control or Hb α siRNA in thepresence or absence of L-NAME. In a-c, n indicates the number ofarteries; value in parenthesis shows number of mice. d, En face view ofa dual immunofluorescence of a mouse TD artery showing Hb α (red) andeNOS (green). The white box in the merge panel indicates the region ofinterest magnified in the right panel. e, Proximity ligation assay forHb α and eNOS (red punctuates) in transverse mouse TD artery sections.Inset shows the negative control. f, Western blot analysis from samplesco-immunoprecipitated for Hb α and blotted for eNOS from isolated TD andcarotid arteries. g, Dual immunofluorescence for Hb α and eNOS ontransverse section from a VCCC. Red indicates Hb α and green shows eNOS.h, Co-immunoprecipitation of Hb α Western blotted for eNOS on VCCClysates. i, Co-immunoprecipitation of purified eNOS-FLAG protein blottedfor Hb α. j, Schematic diagram of experimental design illustrating acannulated vessel with transfected Hb α siRNA showing NO diffusion as areadout. k, NO diffusion results from mouse TD arteries transfected withcontrol or Hb α siRNA (n≧5). 1, Illustration of experimental setup forVCCC experiments. in, NO diffusion results from VCCCs transfected withcontrol or Hb α siRNA. (n≧4). In k striped bars represent ex vivo dataand in m open bars indicate in vitro data. In a-c, * shows significancebetween control siRNA vs. Hb α siRNA, ^ indicates significance betweenHb α siRNA vs. Hb α siRNA+L-NAME and ♦ represents significance betweencontrol vs. control+L-NAME. In d-e scale bar is 10 μm and in g 1 μm. Ink and m n.s indicates not significant. In e, L indicates the lumen. pvalues are shown for each comparison. All error bars represent s.e.m.

FIG. 3—The oxidation state of Hb α resides in a mixture of Fe²⁺ andFe³⁺. a, Ultraviolet-visible spectroscopy analysis of TD arteries and cVCCC fractions. The inset in a indicates the region of interest (magentabox) of the Soret (˜420 nm) and Q bands (˜540-575 nm). b, measurement ofHb α oxidation state calculating the ratio of Fe²⁺ to Fe³⁺ in TDarteries (n=3) and d VCCC fractions (n=3) with and without Hb α siRNA.When MEJ fractions were studied, a Soret peak (˜410 nm) characteristicof the Fe³⁺ state (methemoglobin) was found (FIG. 3c ). In b stripedbars indicate ex vivo data and in d open bars represent in vitro data. pvalues are indicated for each comparison. All error bars represents.e.m.

FIG. 4—CytB5R3 expression and activity play a role in vasomotor tone andNO diffusion. a, Immunofluorescence of CytB5R3 expression (red) andnuclei (blue). Green represents autofluorescence from internal elasticlamina. b, TEM analysis of CytB5R3 expression at the MEJ (blackparticles) in vivo. c, Western blot analysis of CytB5R3 in TD arteriesand d in VCCC. e, Immunofluorescence of CytB5R3 expression in the VCCC.Red shows CytB5R3 and green indicates F-actin. f, En face view of a dualimmunofluorescence labeling of a mouse TD artery showing Hb α (red) andCyB5R3 (green) in upper panels. White box in the merge image in thelower left panel shows the region of interest magnified in the lowerright panel. g, Colocalization of CytB5R3 (red) and Hb α (green) on atransverse section from the VCCC. h, Proximity ligation assay for Hb αand CytB5R3 (red punctuates) on transverse mouse TD artery sections.Inset shows the negative control. Green shows internal elastic laminaautofluorescence. i, Western blot analysis from samplesco-immunoprecipitated for Hb α and blotted for CytB5R3 from isolated TDand carotid arteries, VCCC or purified proteins. j, Time course to 50 μMPE, k dose response to PE and 1 dose response to Ach on TD arteriestreated with control or Hb α siRNA in the presence or absence of L-NAME.In j-l, n indicates the number of arteries; value in parenthesis showsnumber of mice. m, Schematic of experimental setup for NO diffusionassay in a cannulated artery that was transfected with CytB5R3 siRNA. n,Results from NO diffusion experiment in mouse TD arteries with geneticknockdown of CytB5R3 expression (n≧3). o, Illustration showing theexperimental setup for VCCC experiments. p, NO diffusion results fromVCCCs transfected with control or CytB5R3 siRNA (n=4). In n striped barsindicate ex vivo data and in p open bars represent in vitro data. Inj-l * shows significance between control siRNA vs. CytB5R3 siRNA, ^indicates significance between CytB5R3 siRNA and CytB5R3 siRNA+L-NAMEand ♦ represents significance between control vs. control+L-NAME. a,Scale bar is 10 μm, b is 0.25 μm, e is 5 μm, f, h are 10 μm and g is 1μm. In a and h L indicates lumen. p values are indicated for eachcomparison. All error bars represent s.e.m.

FIG. 5—NO diffusion is limited following PE stimulation. a, Vascularreactivity of TD arteries in the presence or absence of the NOSinhibitor L-NAME following 50 μM PE stimulation. n indicates the numberof arteries; value in parenthesis shows number of mice. * representssignificant differences of p<0.05. b, Measurement of cGMP accumulationafter PE application in SMCs of VCCC in the presence or absence ofL-NAME (n≧4). c-d, Time course for cGMP accumulation following PEstimulation (n=4). e, Schematic illustration showing PE application toTD arteries or f SMCs in a VCCC followed by f, measurements of NOrelease (NO_(x)). g, Time course evaluation of NO_(x) accumulation inthe extracellular milieu of TD arteries or h VCCCs following PEstimulation. In b, c, g, and h n.s. means not significant. In b, d and hopen bars represent in vitro data and in c, g, striped bars indicate exvivo data. P values are shown for each comparison. All error barsrepresent s.e.m.

FIG. 6—Flow chart representing the proteomic screen of VCCC lysatesusing iTRAQ. Step 1, EC and SMC cells were grown on Transwells and EC,MEJ, and SMC fractions were isolated according to materials and methods.Step 2, 25 μgs of EC MEJ and SMC protein were separately reduced andcysteines were blocked as described in the iTRAQ™ kit (AppliedBiosystems). Step 3, after overnight trypsin digestion, samples werelabeled on the N-terminal amino group and epsilon amino group of lysineresidues with iTRAQ tags as follows: EC-iTRAQ 113, MEF-iTRAQ 115 andSMC-iTRAQ 117. The labeled samples were pooled together and subjected toa strong cation exchange column separating the samples into 20 fractions(Step 4). Step 5, samples were subjected to QSTAR XL LC-MS/MS analysisand data was collected by electrospray ionization using an AppliedBiosystems API QSTAR XL mass spectrometer. Results generated wereprocessed using Mascot Distiller and the database was searched usingMascot Server, and protein validation was confirmed usingProteinProphet. iTRAQ quantitations performed using Paragon™ searchalgorithm in ProteinProphet software, Peptide fragments (gray show overpeak) and simultaneous quantification of reporter ions (isobarictags-inset) were used for determination of enriched proteins at the MEJ.Proteins in the MEJ fraction enriched compared to the EC or SMC lysateswere considered positive.

FIG. 7, comprising 7A to 7D—Results from iTRAQ analysis. List ofproteins enriched at the MEJ determined by differences in the ratios ofMEJ:EC and MEJ:SMC. The Protein ID column represents the specificidentification for each of the proteins. The Protein Name indicates thespecific protein that was identified and enriched at the MEJ. ThePercent Coverage signifies how much of the total protein sequence wasidentified. The # of Distinct Peptides shows how many peptides werefound during the analysis. The Ration of MEJ:EC or MEJ:SMC representsthe ratiometric enrichment of each protein the MEJ. Highlighted in greenis Hb α showing enrichment compared to EC or SMC monolayers. 7A. ProteinID numbers IPI00930226 to IPI00747810. 7B. Protein ID numbersIPI00219018 to IPI00304596. 7C. Protein ID numbers IPI00549248 toIPI00465028. 7D. Protein ID numbers IPI00010779 to RRRRRnull withprotein name REVERSED Gene_symbol=VPs13D.

FIG. 8—Hb α is enriched at the MEJ in co-cultured HUVECs and HUVSMCs. 8AQuantitative Western blot analysis of EC, MEJ, and SMC lysates for Hb α.GAPDH was used as a loading and normalization control for 8B,quantitation. (n=4). P values are indicated for each comparison. Allerror bars represent s.e.m.

FIG. 9—Expression of Hb α in multiple vascular beds. Immunofluorescenceanalysis of Hb α expression (red) in mouse epigastric abdominal feedartery, mesenteric artery and aorta. Blue represents nuclei and greenindicates autofluorescence from internal elastic lamina. L is lumen.Scale bar is 25 μm.

FIG. 10—The effect of cell type specific transfection of Hb α siRNA inthe VCCC. Quantitative immunoblot analysis (10A1—Immunoblot; 10A2—Graphof quantitative results of A1) of Hb α expression in isolated MEJfractions from VCCCs following cell-type specific knockdown of Hb αusing siRNA. GAPDH served as a loading control (n=3). Western blotanalysis (10B1 and 10B2) of Hb α and eNOS protein expression from ECstransfected with Hb α siRNA in VCCCs. GAPDH served as a loading control.10B1—Western blot; 10B2—Graph of quantitative results of 10B1) p valuesare shown for each composition. All error bars represent s.e.m.

FIG. 11—Effects of decreased Hb α protein on eNOS and CytB5R3 proteinexpression at the MEJ. Western blot analysis (11A) of CytB5R3 (depictedgraphically in 11C) and eNOS (depicted graphically in 11B) proteinexpression at the MEJ from ECs, SMCs or both transfected with Hb siRNAin VCCCs. GAPDH served as a loading control (n=3). n.s. indicates notsignificant. All error bars represent s.e.m.

FIG. 12, comprising 12A1, 12A2, 12B1, 12B2, 12C1, 12C2, and 12D—mRNAanalysis of myoglobin, neuroglobin and cytoglobin in vivo and in vitroand protein expression of cytoglobin in SMCs. mRNA expression ofmyoglobin in vitro (12A1) or in vivo (12A2); neuroglobin in vitro (12B1)and in vivo (12B2); and cytoglobin in VCCC and in arteries(12C1—cytoglobin in vitro; 12C2—cytoglobin in vivo). The skin or brainwas used as a positive control. All samples were normalized to B2M.12D—Western blot analysis of cytoglobin expression in the VCCC model.GAPDH served as a loading control.

FIG. 13—Hb α stabilizing protein expression in TD arteries and in theVCCC. 13A, Immunofluorescence analysis of AHSP expression (red) in TDarteries. Blue represents nuclei and green indicates autofluorescencefrom internal elastic lamina. L is lumen. Scale bar is 25 μm.Quantitative Western blot (13B1) of AHSP in the VCCC model depictedgraphically in 13B2. GAPDH served as a loading control (n=3). p valuesare indicated for each comparison. n.s. indicates not significant. Allerror bars represent s.e.m.

FIG. 14—Expression of HB α followed siRNA knockdown in TD arteries. Enface immunofluorescence of Hb α expression following siRNA knockdown inECs. Red indicates Hb α expression and blue shows labeled nuclei. Scalebar is 10 m.

FIG. 15—Effect of basal tone after siRNA transfection or PTU treatment.a, Measurement of basal tone (initial diameter/maximal diameter×100) forarteries transfected with Hb α and CytB5R3 siRNA or b, PTU. n≧4.

FIG. 16—NO is primarily consumed in TD arteries and MEJ lysates and NOdiffusion is inhibited with CO. Measurement of NO consumption fromisolated carotid or TD arteries (16A1 and 16A2) or EC MEJ, or SMCslysates (16B1 and 16B2) (n≧3). The tracings in 16A1 and 16B1 show thedifferences in NO consumption measured by Seivers NO analyzer and 16A2and 16B2 depict NO diffusion. 16C, NO diffusion in mouse TD arteries(n≧3) or 16D, VCCCs (n=5) that were pretreated with carbon monoxide. In16A2 and 16C, striped bars represent ex vivo data an in 16B2 and 16Dopen bars indicate in vitro data. p values are indicated for eachcomparison. All error bars represent s.e.m.

FIG. 17—Membrane precipitates from VCCC fractions. Image of membraneproteins showing a brown pellet characteristic of methemoglobin in theMEJ lysate.

FIG. 18—Decreased Hb α expression in TD arteries or in the VCCC resultsin decreased S-nitrosothiol formation. a, Schematic diagram ofexperimental design illustrating a cannulated vessel with transfected HBα si RNA showing S-nitrosothiol formation as a readout. b, Effect of Hbα expression on S-nitrosothiol synthesis in isolated TD arteries (n=3).c, Illustration of experimental setup for VCCC experiments. d, Measureof S-nitrosothiol generation in the VCCC following knockdown of HB α(n=4). In b and d n.s. indicates not significant. p values are shown foreach composition. All error bars represent s.e.m.

FIG. 19—Molecular modeling of potential interaction sites of Hb α, eNOSand CytB5R3. Molecular model of potential docking sites based on theknown crystal structures of Hb α (1Y01), CytB5R3 (1UMK) and eNOS (3NOS).The final model consists of a Hb α/CytB5R3 homodimer docked to the eNOSdimer and is represented as a low-resolution model surfacerepresentation so that the exact interfaces are not over interpreted.

FIG. 20—Loss-or-gain of CytB5R3 function in ECs alters methemoglobin αreduction. Immunoblots of lysates from transfected ECs with CytB5R3siRNA (20A1) or CytB5R3-Flag (20A2). Measurements of met-Hb α reductionusing ultraviolet-visible spectroscopy from control (20B1), CytB5R3siRNA (20B2), or CytB5R3-Flag (20B3) transfect ECs. Arrows indicate theprogression of the absorbance spectra over time. The absorbance areawith light color represents 0-3 minute differences and the dark colorshows 3-10 minute changes. (20C) The inset shows regions of interest formet-Hb α reduction. Met-Hb α differences were measured by calculatingthe change in area for 0-3 and 0-10 minutes for each condition. Thegraph represents met-Hb α reduction as a function of time.

FIG. 21—Knockdown efficiency of CytB5R3 in isolated arteries and theVCCC and the effects of CytB5R3 loss on eNOS and HB α proteinexpression. En face immunofluorescence (21A) or quantitative Westernblot analysis of CytB5R3 expression in isolated MEJ fractions from VCCCsfollowing cell type specific knockdown using siRNA (21B1—Western blot;21B2—graphic depiction of quantitation of 21B1). GAPDH served as aloading and normalization control (n=3). Green indicates CytB5R3expression and blue signifies nuclei. 21C1 shows immunoblots of CytB5R3and eNOS expression in EC monolayers from the VCCC transfected withCytB5R3 siRNA which are graphically depicted in 21C2. 21D1 and21D2—Western blot analysis of eNOS and Hb α protein expression at theMEJ from ECs, SMCs or both transfected with CytB5R3 siRNA in VCCCs(21D1) and are graphically depicted in 21D2 (eNOS) and 21D3 (Hbα). Scalebar is 10 μm. p values are shown for each comparison. All error barsrepresent s.e.m.

FIG. 22—Inhibited activity of CytB5R3 with PTU alters vascularreactivity and NO diffusion. a, Time course to PE, b dose response to PEor c dose response to ACH on TD arteries treated with control or PTU inthe presence or absence of L-NAME. n indicates the number of arteries;value in parenthesis shows number of mice. The inset graph in brepresents TD arteries treat with control, PTU or L-thyroxin (50 μM)+PTUfollowed by stimulation with 10 μM PE (n=4). d, Schematic diagram ofexperimental design illustrating a cannulated vessel treated with PTUshowing NO diffusion as a readout. e, NO diffusion results from mouse TDarteries treated with PTU (n=4). f, Illustration of experimental setupfor VCCC experiments with PTU. g, NO diffusion results from VCCCsincubated with PTU. (n≧3). In e striped bars represent ex vivo data andin m open bars indicate in vitro data. In a and b * shows significancebetween control vs. PTU, ^ indicates significance between PTU vs.PTU+L-NAME and black diamond represents significance between control vs.L-NAME. p values are shown for each comparison. All error bars represents.e.m.

FIG. 23—In silico modeling of human eNOS and Hb α crystal structures andidentification of a conserved interaction sequence on Hb α. In silicomodeling of the PDB crystal structures for eNOS (gray; 3NOS) and Hb α(orange; 1Y01) using GRAMMX server. The magnified image on right showsthe interacting region of Hb α (ribbon structure) that interacts witheNOS (dark gray region). The identified Hb α sequence is below and wasblasted against other mammalian species showing conserved sequenceshighlighted in yellow.

FIG. 24—Hb α X peptide disrupts the interaction between eNOS and Hb α.24A Schematic of experimental set up testing Hb α X specificity usingpurified proteins: 1) Flag-eNOS was incubated with tat, Scr X, or Hb αX, 2) Flag-eNOS+peptide complexes were incubated with purified Hb αchains, 3) anti-Flag beads were mixed with Flag-eNOS+peptides, and 4)complexes were precipitated. 24B1 and 24B2, Western blot analysis ofFlag-eNOS input, Hb α input and Hb α precipitated with Flag-eNOS (n=3).

FIG. 25—Hb α X peptide disrupts the eNOS and Hb α complex inthoracodorsal arteries. 25A Proximity ligation assay for eNOS and Hb α(red punctuates) on transverse sections of a mouse thoracodorsal artery.Green shows internal elastic lamina autofluorescence. 25B, The graph onright shows quantitation of red punctates from the proximity ligationassay (n=3). 25C, En face immunofluorescence of Alexa hydrazide 633(magenta), FITC labeled Hb α X (green) and Hb α (red) on mousethoracodorsal arteries. Graphs (25D1 and 25D2) show quantitation ofcolocalized FITC labeled Hb α X and Hb α in IEL holes. Scale bar is 10μm in 25A and 25C. L indicates lumen and IEL is internal elastic lamina.In 25B * indicates significance between conditions and all error barsrepresent s.e.m.

FIG. 26—Hb α X peptide increases nitric oxide signaling in the vesselwall of wildtype but not eNOS^(−/−) mice. a, Measurement of cGMPaccumulation following phenylephrine stimulation in thoracodorsalarteries pretreated with Scr X or Hb α X peptide in the presence ofL-NAME (n=3). b, Dose response to phenylephrine on arteries treated withScr X or Hb α X in the presence or absence of L-NAME. c, Cumulative doseresponse curve on thoracodorsal arteries from eNOS' animals with Scr Xor Hb α X. In b and c, n indicates the number of arteries; value inparenthesis shows number of mice. In b and c, * shows significancebetween Scr X vs. Hb α X, ^ indicates significance between Hb α X vs. Hbα X+L-NAME analyzed using 1-way ANOVA. All error bars represent s.e.m.

FIG. 27—Hb α X peptide does not change eNOS phosphorylation, NO releasein untreated and treated coronary endothelial cells. Western blotanalysis of pS1177 eNOS and total eNOS from human coronary endothelialcells incubated with Scr X or Hb α X (n=3) (27A1, 27A2, 27A3). Nitritemeasurements from unstimulated and stimulated (10 μM bradykinin, 5minutes) human coronary endothelial cells treated with Scr X or Hb α X(27B1, 27B2, 27B3). In a and b n=3.

FIG. 28—Dose response to phenylephrine presented as a change in micronson arteries treated with Scr X or Hb α X in the presence or absence ofL-NAME. n indicates the number of arteries; value in parenthesis showsnumber of mice. All error bars represent s.e.m.

FIG. 29—Effects of Hb α X peptide on wildtype abdominal aortas.Cumulative dose response curve to PE from murine C57BL/6 abdominalaortic rings treated with control, Scr X or Hb α X. All error barsrepresent s.e.m.

FIG. 30—Hb α X peptide decreases blood pressure, but not in eNOS^(−/−)mice. Radio telemetry measurements of systolic, diastolic and meanarterial blood pressure from mice injected with saline, Scr X or Hb α Xpeptide from C57BL/6 (30A1—Systolic Pressure; 30A2—Diastolic Pressure;30A3—MAP) or eNOS^(−/−) (30B1—Systolic; 30B2—Diastolic; 30B3—MAP) mice.Significant differences are indicated with * and analyzed by a 1-wayANOVA followed by a Bonferroni's post-hoc test. n≧4 mice for allconditions; error bars indicate s.e.m.

DETAILED DESCRIPTION Abbreviations and Acronyms

-   -   5-HT—5-hydroxytryptamine    -   AHSP—alpha hemoglobin stabilizing protein    -   Ach—acetylcholine    -   CCRC—cumulative concentration response curves    -   CO—carbon monoxide    -   CtyB5R3—cytochrome B5 reductase 3    -   DETA        NONOate—(Z)-1-[2-(2-Aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate        (an NO donor)    -   EC—endothelial cell (in some experiments it stands for human        coronary ECs)    -   EC₅₀—50% of maximal effective concentration    -   eNOS—endothelial NOS    -   Hb—hemoglobin    -   Hb α—hemoglobin alpha    -   HUVEC—human umbilical vein endothelial cell    -   HUVSMC—human umbilical vein smooth muscle cell    -   IBMX—3-isobutyl-1-methylxanthine    -   IF—immunofluorescence    -   IP—immunoprecipitation    -   iTEM—immuno TEM    -   iTRAQ—isobaric tags for relative and absolute quantitation    -   L-NAME—L-N^(G)-nitroarginine methyl ester (a NOS inhibitor)    -   MEJ—myoendothelial junction    -   NO—nitric oxide    -   NOA—NO analyzer    -   NOS—NO synthase    -   PE—phenylephrine    -   PLA—proximity ligation assay    -   PTU—propylthiouracil    -   siRNA—small interfering RNA    -   SMC—smooth muscle cell    -   SNO-NAC—S-nitrosylated N-Acetyl cysteine    -   TD—thoracodorsal    -   TEM—transmission electron microscopy    -   VCCC—vascular cell co-culture    -   WB—western blot

Definitions

In describing and claiming the invention, the following terminology willbe used in accordance with the definitions set forth below. Unlessdefined otherwise, all technical and scientific terms used herein havethe commonly understood definition by one of ordinary skill in the artto which the invention pertains. Other methods and materials similar orequivalent to those described herein may be useful in the practice ortesting of the present invention.

The articles “a” and “an” are used herein to refer to one or to morethan one (i.e., to at least one) of the grammatical object of thearticle. By way of example, “an element” means one element or more thanone element.

The term “about,” as used herein, means approximately, in the region of,roughly, or around. When the term “about” is used in conjunction with anumerical range, it modifies that range by extending the boundariesabove and below the numerical values set forth. For example, in oneaspect, the term “about” is used herein to modify a numerical valueabove and below the stated value by a variance of 20%.

The terms “additional therapeutically active compound” or “additionaltherapeutic agent,” as used in the context of the present invention,refers to the use or administration of a compound for an additionaltherapeutic use for a particular injury, disease, or disorder beingtreated. Such a compound, for example, could include one being used totreat an unrelated disease or disorder, or a disease or disorder whichmay not be responsive to the primary treatment for the injury, diseaseor disorder being treated.

As use herein, the terms “administration of” and or “administering” acompound should be understood to mean providing a compound of theinvention or a prodrug of a compound of the invention to a subject inneed of treatment.

As used herein, an “agonist” is a composition of matter which, whenadministered to a mammal such as a human, enhances or extends abiological activity attributable to the level or presence of a targetcompound or molecule of interest in the subject.

As used herein, “alleviating a disease or disorder symptom,” meansreducing the severity of the symptom or the frequency with which such asymptom is experienced by a subject, or both.

As used herein, an “analog,” or “analogue” of a chemical compound is acompound that, by way of example, resembles another in structure but isnot necessarily an isomer (e.g., 5-fluorouracil is an analog ofthymine).

An “antagonist” is a composition of matter which when administered to amammal such as a human, inhibits a biological activity attributable tothe level or presence of a compound or molecule of interest in thesubject.

The term “antimicrobial agents” as used herein refers to anynaturally-occurring, synthetic, or semi-synthetic compound orcomposition or mixture thereof, which is safe for human or animal use aspracticed in the methods of this invention, and is effective in killingor substantially inhibiting the growth of microbes. “Antimicrobial” asused herein, includes antibacterial, antifungal, and antiviral agents.

An “aptamer” is a compound that is selected in vitro to bindpreferentially to another compound (for example, the identified proteinsherein). Often, aptamers are nucleic acids or peptides because randomsequences can be readily generated from nucleotides or amino acids (bothnaturally occurring or synthetically made) in large numbers but ofcourse they need not be limited to these.

As used herein, the term “attach,” or “attachment,” or “attached,” or“attaching,” used herein interchangeably with “bind,” or “binding” or“binds” or “bound” refers to any physical relationship between moleculesthat results in forming a stable complex, such as a physicalrelationship between a ligand, such as a peptide or small molecule, witha “binding partner” or “receptor molecule.” The relationship may bemediated by physicochemical interactions including, but not limited to,a selective noncovalent association, ionic attraction, hydrogen bonding,covalent bonding, Van der Waals forces or hydrophobic attraction.

The term “binding” refers to the adherence of molecules to one another,such as, but not limited to, enzymes to substrates, ligands toreceptors, antibodies to antigens, DNA binding domains of proteins toDNA, and DNA or RNA strands to complementary strands.

“Binding partner,” as used herein, refers to a molecule capable ofbinding to another molecule.

The term “biological sample,” as used herein, refers to samples obtainedfrom a subject, including, but not limited to, sputum, CSF, blood,serum, plasma, gastric aspirates, throat swabs, skin, hair, tissue,blood, plasma, serum, cells, sweat and urine.

As used herein, the term “carrier molecule” refers to any molecule thatis chemically conjugated to the antigen of interest that enables animmune response resulting in antibodies specific to the native antigen.

A “chamber”, as used herein, refers to something to which a solution canbe added, such as a tube or well of a multiwell plate, etc.

As used herein, the term “chemically conjugated,” or “conjugatingchemically” refers to linking the antigen to the carrier molecule. Thislinking can occur on the genetic level using recombinant technology,wherein a hybrid protein may be produced containing the amino acidsequences, or portions thereof, of both the antigen and the carriermolecule. This hybrid protein is produced by an oligonucleotide sequenceencoding both the antigen and the carrier molecule, or portions thereof.This linking also includes covalent bonds created between the antigenand the carrier protein using other chemical reactions, such as, but notlimited to glutaraldehyde reactions. Covalent bonds may also be createdusing a third molecule bridging the antigen to the carrier molecule.These cross-linkers are able to react with groups, such as but notlimited to, primary amines, sulfhydryls, carbonyls, carbohydrates, orcarboxylic acids, on the antigen and the carrier molecule. Chemicalconjugation also includes non-covalent linkage between the antigen andthe carrier molecule.

A “coding region” of a gene consists of the nucleotide residues of thecoding strand of the gene and the nucleotides of the non-coding strandof the gene which are homologous with or complementary to, respectively,the coding region of an mRNA molecule which is produced by transcriptionof the gene.

The term “competitive sequence” refers to a peptide or a modification,fragment, derivative, or homolog thereof that competes with anotherpeptide for its cognate binding site.

“Complementary” as used herein refers to the broad concept of subunitsequence complementarity between two nucleic acids, e.g., two DNAmolecules. When a nucleotide position in both of the molecules isoccupied by nucleotides normally capable of base pairing with eachother, then the nucleic acids are considered to be complementary to eachother at this position. Thus, two nucleic acids are complementary toeach other when a substantial number (at least 50%) of correspondingpositions in each of the molecules are occupied by nucleotides whichnormally base pair with each other (e.g., A:T and G:C nucleotide pairs).Thus, it is known that an adenine residue of a first nucleic acid regionis capable of forming specific hydrogen bonds (“base pairing”) with aresidue of a second nucleic acid region which is antiparallel to thefirst region if the residue is thymine or uracil. Similarly, it is knownthat a cytosine residue of a first nucleic acid strand is capable ofbase pairing with a residue of a second nucleic acid strand which isantiparallel to the first strand if the residue is guanine. A firstregion of a nucleic acid is complementary to a second region of the sameor a different nucleic acid if, when the two regions are arranged in anantiparallel fashion, at least one nucleotide residue of the firstregion is capable of base pairing with a residue of the second region.In one embodiment, the first region comprises a first portion and thesecond region comprises a second portion, whereby, when the first andsecond portions are arranged in an antiparallel fashion, at least about50%, including at least about 75%, at least about 90%, or at least about95% of the nucleotide residues of the first portion are capable of basepairing with nucleotide residues in the second portion. In oneembodiment, all nucleotide residues of the first portion are capable ofbase pairing with nucleotide residues in the second portion.

A “compound,” as used herein, refers to any type of substance or agentthat is commonly considered a drug, or a candidate for use as a drug, aswell as combinations and mixtures of the above. When referring to acompound of the invention, and unless otherwise specified, the term“compound” is intended to encompass not only the specified molecularentity but also its pharmaceutically acceptable, pharmacologicallyactive analogs, including, but not limited to, salts, polymorphs,esters, amides, prodrugs, adducts, conjugates, active metabolites, andthe like, where such modifications to the molecular entity areappropriate.

A “control” cell is a cell having the same cell type as a test cell. Thecontrol cell may, for example, be examined at precisely or nearly thesame time the test cell is examined. The control cell may also, forexample, be examined at a time distant from the time at which the testcell is examined, and the results of the examination of the control cellmay be recorded so that the recorded results may be compared withresults obtained by examination of a test cell.

A “test” cell is a cell being examined.

The term “delivery vehicle” refers to any kind of device or materialwhich can be used to deliver compounds in vivo or can be added to acomposition comprising compounds administered to a plant or animal. Thisincludes, but is not limited to, implantable devices, aggregates ofcells, matrix materials, gels, etc.

As used herein, a “derivative” of a compound refers to a chemicalcompound that may be produced from another compound of similar structurein one or more steps, as in replacement of H by an alkyl, acyl, or aminogroup.

As used herein, a “detectable marker” or a “reporter molecule” is anatom or a molecule that permits the specific detection of a compoundcomprising the marker in the presence of similar compounds without amarker. Detectable markers or reporter molecules include, e.g.,radioactive isotopes, antigenic determinants, enzymes, nucleic acidsavailable for hybridization, chromophores, fluorophores,chemiluminescent molecules, electrochemically detectable molecules, andmolecules that provide for altered fluorescence-polarization or alteredlight-scattering.

A “disease” is a state of health of an animal wherein the animal cannotmaintain homeostasis, and wherein if the disease is not ameliorated thenthe animal's health continues to deteriorate.

In contrast, a “disorder” in an animal is a state of health in which theanimal is able to maintain homeostasis, but in which the animal's stateof health is less favorable than it would be in the absence of thedisorder. Left untreated, a disorder does not necessarily cause afurther decrease in the animal's state of health.

As used herein, the term “domain” refers to a part of a molecule orstructure that shares common physicochemical features, such as, but notlimited to, hydrophobic, polar, globular and helical domains orproperties such as ligand binding, signal transduction, cell penetrationand the like. Specific examples of binding domains include, but are notlimited to, DNA binding domains and ATP binding domains.

As used herein, an “effective amount” or “therapeutically effectiveamount” means an amount sufficient to produce a selected effect, such asalleviating symptoms of a disease or disorder. In the context ofadministering compounds in the form of a combination, such as multiplecompounds, the amount of each compound, when administered in combinationwith another compound(s), may be different from when that compound isadministered alone. Thus, an effective amount of a combination ofcompounds refers collectively to the combination as a whole, althoughthe actual amounts of each compound may vary. The term “more effective”means that the selected effect is alleviated to a greater extent by onetreatment relative to the second treatment to which it is beingcompared.

As used herein, the term “effector domain” refers to a domain capable ofdirectly interacting with an effector molecule, chemical, or structurein the cytoplasm which is capable of regulating a biochemical pathway.

“Encoding” refers to the inherent property of specific sequences ofnucleotides in a polynucleotide, such as a gene, a cDNA, or an mRNA, toserve as templates for synthesis of other polymers and macromolecules inbiological processes having either a defined sequence of nucleotides(i.e., rRNA, tRNA and mRNA) or a defined sequence of amino acids and thebiological properties resulting therefrom. Thus, a gene encodes aprotein if transcription and translation of mRNA corresponding to thatgene produces the protein in a cell or other biological system. Both thecoding strand, the nucleotide sequence of which is identical to the mRNAsequence and is usually provided in sequence listings, and thenon-coding strand, used as the template for transcription of a gene orcDNA, can be referred to as encoding the protein or other product ofthat gene or cDNA.

The term “epitope” as used herein is defined as small chemical groups onthe antigen molecule that can elicit and react with an antibody. Anantigen can have one or more epitopes. Most antigens have many epitopes;i.e., they are multivalent. In general, an epitope is roughly five aminoacids or sugars in size. One skilled in the art understands thatgenerally the overall three-dimensional structure, rather than thespecific linear sequence of the molecule, is the main criterion ofantigenic specificity.

As used herein, an “essentially pure” preparation of a particularprotein or peptide is a preparation wherein at least about 95%,including at least about 99%, by weight, of the protein or peptide inthe preparation is the particular protein or peptide.

As used in the specification and the appended claims, the terms “forexample,” “for instance,” “such as,” “including” and the like are meantto introduce examples that further clarify more general subject matter.Unless otherwise specified, these examples are provided only as an aidfor understanding the invention, and are not meant to be limiting in anyfashion.

The terms “formula” and “structure” are used interchangeably herein.

A “fragment” or “segment” is a portion of an amino acid sequence,comprising at least one amino acid, or a portion of a nucleic acidsequence comprising at least one nucleotide. The terms “fragment” and“segment” are used interchangeably herein.

As used herein, the term “fragment,” as applied to a protein or peptide,can ordinarily be at least about 3-15 amino acids in length, at leastabout 15-25 amino acids, at least about 25-50 amino acids in length, atleast about 50-75 amino acids in length, at least about 75-100 aminoacids in length, and greater than 100 amino acids in length.

As used herein, the term “fragment” as applied to a nucleic acid, mayordinarily be at least about 20 nucleotides in length, typically, atleast about 50 nucleotides, more typically, from about 50 to about 100nucleotides, including at least about 100 to about 200 nucleotides,including at least about 200 nucleotides to about 300 nucleotides,including at least about 300 to about 350, including at least about 350nucleotides to about 500 nucleotides, including at least about 500 toabout 600, including at least about 600 nucleotides to about 620nucleotides, including at least about 620 to about 650, and includingthe embodiment wherein the nucleic acid fragment will be greater thanabout 650 nucleotides in length.

As used herein, a “functional” molecule is a molecule in a form in whichit exhibits a property or activity by which it is characterized. Afunctional enzyme, for example, is one that exhibits the characteristiccatalytic activity by which the enzyme is characterized.

“Homologous” as used herein, refers to the subunit sequence similaritybetween two polymeric molecules, e.g., between two nucleic acidmolecules, e.g., two DNA molecules or two RNA molecules, or between twopolypeptide molecules. When a subunit position in both of the twomolecules is occupied by the same monomeric subunit, e.g., if a positionin each of two DNA molecules is occupied by adenine, then they arehomologous at that position. The homology between two sequences is adirect function of the number of matching or homologous positions, e.g.,if half (e.g., five positions in a polymer ten subunits in length) ofthe positions in two compound sequences are homologous then the twosequences are 50% homologous, if 90% of the positions, e.g., 9 of 10,are matched or homologous, the two sequences share 90% homology. By wayof example, the DNA sequences 3′ATTGCC5′ and 3′TATGGC share 50%homology.

As used herein, “homology” is used synonymously with “identity.”

The determination of percent identity between two nucleotide or aminoacid sequences can be accomplished using a mathematical algorithm. Forexample, a mathematical algorithm useful for comparing two sequences isthe algorithm of Karlin and Altschul (1990, Proc. Natl. Acad. Sci. USA87:2264-2268), modified as in Karlin and Altschul (1993, Proc. Natl.Acad. Sci. USA 90:5873-5877). This algorithm is incorporated into theNBLAST and XBLAST programs of Altschul, et al. (1990, J. Mol. Biol.215:403-410), and can be accessed, for example at the National Centerfor Biotechnology Information (NCBI) world wide web site. BLASTnucleotide searches can be performed with the NBLAST program (designated“blastn” at the NCBI web site), using the following parameters: gappenalty=5; gap extension penalty=2; mismatch penalty=3; match reward=1;expectation value 10.0; and word size=11 to obtain nucleotide sequenceshomologous to a nucleic acid described herein. BLAST protein searchescan be performed with the XBLAST program (designated “blastn” at theNCBI web site) or the NCBI “blastp” program, using the followingparameters: expectation value 10.0, BLOSUM62 scoring matrix to obtainamino acid sequences homologous to a protein molecule described herein.To obtain gapped alignments for comparison purposes, Gapped BLAST can beutilized as described in Altschul et al. (1997, Nucleic Acids Res.25:3389-3402). Alternatively, PSI-Blast or PHI-Blast can be used toperform an iterated search which detects distant relationships betweenmolecules (Id.) and relationships between molecules which share a commonpattern. When utilizing BLAST, Gapped BLAST, PSI-Blast, and PHI-Blastprograms, the default parameters of the respective programs (e.g.,XBLAST and NBLAST) can be used.

The percent identity between two sequences can be determined usingtechniques similar to those described above, with or without allowinggaps. In calculating percent identity, typically exact matches arecounted.

The term “inhibit,” as used herein, refers to the ability of a compound,agent, or method to reduce or impede a described function, level,activity, rate, etc., based on the context in which the term “inhibit”is used. In one embodiment, inhibition is by at least 10%. The term“inhibit” is used interchangeably with “reduce” and “block.”

The term “inhibit a complex,” as used herein, refers to inhibiting theformation of a complex or interaction of two or more proteins, as wellas inhibiting the function or activity of the complex. The term alsoencompasses disrupting a formed complex. However, the term does notimply that each and every one of these functions must be inhibited atthe same time.

The term “inhibit a protein,” as used herein, refers to any method ortechnique which inhibits protein synthesis, levels, activity, orfunction, as well as methods of inhibiting the induction or stimulationof synthesis, levels, activity, or function of the protein of interest.The term also refers to any metabolic or regulatory pathway which canregulate the synthesis, levels, activity, or function of the protein ofinterest. The term includes binding with other molecules and complexformation. Therefore, the term “protein inhibitor” refers to any agentor compound, the application of which results in the inhibition ofprotein function or protein pathway function. However, the term does notimply that each and every one of these functions must be inhibited atthe same time.

The term “inhibitor” as used herein, refers to any compound or agent,the application of which results in the inhibition of a process orfunction of interest, including, but not limited to, differentiation andactivity. Inhibition can be inferred if there is a reduction in theactivity or function of interest.

As used herein “injecting or applying” includes administration of acompound of the invention by any number of routes and means including,but not limited to, topical, oral, buccal, intravenous, intramuscular,intra arterial, intramedullary, intrathecal, intraventricular,transdermal, subcutaneous, intraperitoneal, intranasal, enteral,topical, sublingual, vaginal, ophthalmic, pulmonary, or rectal means.

As used herein, an “instructional material” includes a publication, arecording, a diagram, or any other medium of expression which can beused to communicate the usefulness of the peptide of the invention inthe kit for effecting alleviation of the various diseases or disordersrecited herein. Optionally, or alternately, the instructional materialmay describe one or more methods of alleviating the diseases ordisorders in a cell or a tissue of a mammal. The instructional materialof the kit of the invention may, for example, be affixed to a containerwhich contains the identified compound invention or be shipped togetherwith a container which contains the identified compound. Alternatively,the instructional material may be shipped separately from the containerwith the intention that the instructional material and the compound beused cooperatively by the recipient.

An “isolated nucleic acid” refers to a nucleic acid segment or fragmentwhich has been separated from sequences which flank it in a naturallyoccurring state, e.g., a DNA fragment which has been removed from thesequences which are normally adjacent to the fragment, e.g., thesequences adjacent to the fragment in a genome in which it naturallyoccurs. The term also applies to nucleic acids which have beensubstantially purified from other components which naturally accompanythe nucleic acid, e.g., RNA or DNA or proteins, which naturallyaccompany it in the cell. The term therefore includes, for example, arecombinant DNA which is incorporated into a vector, into anautonomously replicating plasmid or virus, or into the genomic DNA of aprokaryote or eukaryote, or which exists as a separate molecule (e.g.,as a cDNA or a genomic or cDNA fragment produced by PCR or restrictionenzyme digestion) independent of other sequences. It also includes arecombinant DNA which is part of a hybrid gene encoding additionalpolypeptide sequence.

As used herein, the term “linkage” refers to a connection between twogroups. The connection can be either covalent or non-covalent, includingbut not limited to ionic bonds, hydrogen bonding, andhydrophobic/hydrophilic interactions.

As used herein, the term “linker” refers to a molecule that joins twoother molecules either covalently or noncovalently, e.g., through ionicor hydrogen bonds or van der Waals interactions, e.g., a nucleic acidmolecule that hybridizes to one complementary sequence at the 5′ end andto another complementary sequence at the 3′ end, thus joining twonon-complementary sequences.

The term “modulate”, as used herein, refers to changing the level of anactivity, function, or process. The term “modulate” encompasses bothinhibiting and stimulating an activity, function, or process.

The term “nucleic acid” typically refers to large polynucleotides. By“nucleic acid” is meant any nucleic acid, whether composed ofdeoxyribonucleosides or ribonucleosides, and whether composed ofphosphodiester linkages or modified linkages such as phosphotriester,phosphoramidate, siloxane, carbonate, carboxymethylester, acetamidate,carbamate, thioether, bridged phosphoramidate, bridged methylenephosphonate, bridged phosphoramidate, bridged phosphoramidate, bridgedmethylene phosphonate, phosphorothioate, methylphosphonate,phosphorodithioate, bridged phosphorothioate or sulfone linkages, andcombinations of such linkages. The term nucleic acid also specificallyincludes nucleic acids composed of bases other than the fivebiologically occurring bases (adenine, guanine, thymine, cytosine anduracil).

As used herein, the term “nucleic acid” encompasses RNA as well assingle and double-stranded DNA and cDNA. Furthermore, the terms,“nucleic acid,” “DNA,” “RNA” and similar terms also include nucleic acidanalogs, i.e. analogs having other than a phosphodiester backbone. Forexample, the so-called “peptide nucleic acids,” which are known in theart and have peptide bonds instead of phosphodiester bonds in thebackbone, are considered within the scope of the present invention. By“nucleic acid” is meant any nucleic acid, whether composed ofdeoxyribonucleosides or ribonucleosides, and whether composed ofphosphodiester linkages or modified linkages such as phosphotriester,phosphoramidate, siloxane, carbonate, carboxymethylester, acetamidate,carbamate, thioether, bridged phosphoramidate, bridged methylenephosphonate, bridged phosphoramidate, bridged phosphoramidate, bridgedmethylene phosphonate, phosphorothioate, methylphosphonate,phosphorodithioate, bridged phosphorothioate or sulfone linkages, andcombinations of such linkages. The term nucleic acid also specificallyincludes nucleic acids composed of bases other than the fivebiologically occurring bases (adenine, guanine, thymine, cytosine anduracil). Conventional notation is used herein to describe polynucleotidesequences: the left-hand end of a single-stranded polynucleotidesequence is the 5′-end; the left-hand direction of a double-strandedpolynucleotide sequence is referred to as the 5′-direction. Thedirection of 5′ to 3′ addition of nucleotides to nascent RNA transcriptsis referred to as the transcription direction. The DNA strand having thesame sequence as an mRNA is referred to as the “coding strand”;sequences on the DNA strand which are located 5′ to a reference point onthe DNA are referred to as “upstream sequences”; sequences on the DNAstrand which are 3′ to a reference point on the DNA are referred to as“downstream sequences.”

The term “nucleic acid construct,” as used herein, encompasses DNA andRNA sequences encoding the particular gene or gene fragment desired,whether obtained by genomic or synthetic methods.

Unless otherwise specified, a “nucleotide sequence encoding an aminoacid sequence” includes all nucleotide sequences that are degenerateversions of each other and that encode the same amino acid sequence.Nucleotide sequences that encode proteins and RNA may include introns.

The term “oligonucleotide” typically refers to short polynucleotides,generally, no greater than about 50 nucleotides. It will be understoodthat when a nucleotide sequence is represented by a DNA sequence (i.e.,A, T, G, C), this also includes an RNA sequence (i.e., A, U, G, C) inwhich “U” replaces “T.”

By describing two polynucleotides as “operably linked” is meant that asingle-stranded or double-stranded nucleic acid moiety comprises the twopolynucleotides arranged within the nucleic acid moiety in such a mannerthat at least one of the two polynucleotides is able to exert aphysiological effect by which it is characterized upon the other. By wayof example, a promoter operably linked to the coding region of a gene isable to promote transcription of the coding region.

As used herein, “parenteral administration” of a pharmaceuticalcomposition includes any route of administration characterized byphysical breaching of a tissue of a subject and administration of thepharmaceutical composition through the breach in the tissue. Parenteraladministration thus includes, but is not limited to, administration of apharmaceutical composition by injection of the composition, byapplication of the composition through a surgical incision, byapplication of the composition through a tissue-penetrating non-surgicalwound, and the like. In particular, parenteral administration iscontemplated to include, but is not limited to, subcutaneous,intraperitoneal, intramuscular, intrasternal injection, and kidneydialytic infusion techniques.

The term “pharmaceutical composition” shall mean a compositioncomprising at least one active ingredient, whereby the composition isamenable to investigation for a specified, efficacious outcome in amammal (for example, without limitation, a human). Those of ordinaryskill in the art will understand and appreciate the techniquesappropriate for determining whether an active ingredient has a desiredefficacious outcome based upon the needs of the artisan.

As used herein, the term “pharmaceutically acceptable carrier” includesany of the standard pharmaceutical carriers, such as a phosphatebuffered saline solution, water, emulsions such as an oil/water orwater/oil emulsion, and various types of wetting agents. The term alsoencompasses any of the agents approved by a regulatory agency of the USFederal government or listed in the US Pharmacopeia for use in animals,including humans.

As used herein, the term “physiologically acceptable” ester or saltmeans an ester or salt form of the active ingredient which is compatiblewith any other ingredients of the pharmaceutical composition, which isnot deleterious to the subject to which the composition is to beadministered.

“Plurality” means at least two.

A “polynucleotide” means a single strand or parallel and anti-parallelstrands of a nucleic acid. Thus, a polynucleotide may be either asingle-stranded or a double-stranded nucleic acid.

“Polypeptide” refers to a polymer composed of amino acid residues,related naturally occurring structural variants, and syntheticnon-naturally occurring analogs thereof linked via peptide bonds,related naturally occurring structural variants, and syntheticnon-naturally occurring analogs thereof.

“Synthetic peptides or polypeptides” means a non-naturally occurringpeptide or polypeptide. Synthetic peptides or polypeptides can besynthesized, for example, using an automated polypeptide synthesizer.Various solid phase peptide synthesis methods are known to those ofskill in the art.

The term “prevent,” as used herein, means to stop something fromhappening, or taking advance measures against something possible orprobable from happening. In the context of medicine, “prevention”generally refers to action taken to decrease the chance of getting adisease or condition.

A “preventive” or “prophylactic” treatment is a treatment administeredto a subject who does not exhibit signs, or exhibits only early signs,of a disease or disorder. A prophylactic or preventative treatment isadministered for the purpose of decreasing the risk of developingpathology associated with developing the disease or disorder.

“Primer” refers to a polynucleotide that is capable of specificallyhybridizing to a designated polynucleotide template and providing apoint of initiation for synthesis of a complementary polynucleotide.Such synthesis occurs when the polynucleotide primer is placed underconditions in which synthesis is induced, i.e., in the presence ofnucleotides, a complementary polynucleotide template, and an agent forpolymerization such as DNA polymerase. A primer is typicallysingle-stranded, but may be double-stranded. Primers are typicallydeoxyribonucleic acids, but a wide variety of synthetic and naturallyoccurring primers are useful for many applications. A primer iscomplementary to the template to which it is designed to hybridize toserve as a site for the initiation of synthesis, but need not reflectthe exact sequence of the template. In such a case, specifichybridization of the primer to the template depends on the stringency ofthe hybridization conditions. Primers can be labeled with, e.g.,chromogenic, radioactive, or fluorescent moieties and used as detectablemoieties.

A “prodrug” refers to an agent that is converted into the parent drug invivo. Prodrugs are often useful because, in some situations, they may beeasier to administer than the parent drug. They may, for instance, bebioavailable by oral administration whereas the parent is not. Theprodrug may also have improved solubility in pharmaceutical compositionsover the parent drug, or may demonstrate increased palatability or beeasier to formulate.

As used herein, the tem “promoter/regulatory sequence” means a nucleicacid sequence which is required for expression of a gene productoperably linked to the promoter/regulator sequence. In some instances,this sequence may be the core promoter sequence and in other instances,this sequence may also include an enhancer sequence and other regulatoryelements which are required for expression of the gene product. Thepromoter/regulatory sequence may, for example, be one which expressesthe gene product in a tissue specific manner.

A “constitutive” promoter is a promoter which drives expression of agene to which it is operably linked, in a constant manner in a cell. Byway of example, promoters which drive expression of cellularhousekeeping genes are considered to be constitutive promoters.

An “inducible” promoter is a nucleotide sequence which, when operablylinked with a polynucleotide which encodes or specifies a gene product,causes the gene product to be produced in a living cell substantiallyonly when an inducer which corresponds to the promoter is present in thecell.

A “tissue-specific” promoter is a nucleotide sequence which, whenoperably linked with a polynucleotide which encodes or specifies a geneproduct, causes the gene product to be produced in a living cellsubstantially only if the cell is a cell of the tissue typecorresponding to the promoter.

As used herein, the tem “purified” and like terms relate to anenrichment of a molecule or compound relative to other componentsnormally associated with the molecule or compound in a nativeenvironment. The term “purified” does not necessarily indicate thatcomplete purity of the particular molecule has been achieved during theprocess. A “highly purified” compound as used herein refers to acompound that is greater than 90% pure.

The term “regulate” refers to either stimulating or inhibiting afunction or activity of interest.

By the term “signal sequence” is meant a polynucleotide sequence whichencodes a peptide that directs the path a polypeptide takes within acell, i.e., it directs the cellular processing of a polypeptide in acell, including, but not limited to, eventual secretion of a polypeptidefrom a cell. A signal sequence is a sequence of amino acids which aretypically, but not exclusively, found at the amino terminus of apolypeptide which targets the synthesis of the polypeptide to theendoplasmic reticulum. In some instances, the signal peptide isproteolytically removed from the polypeptide and is thus absent from themature protein.

By “small interfering RNAs (siRNAs)” is meant, inter alia, an isolateddsRNA molecule comprised of both a sense and an anti-sense strand. Inone aspect, it is greater than 10 nucleotides in length. siRNA alsorefers to a single transcript which has both the sense and complementaryantisense sequences from the target gene, e.g., a hairpin. siRNA furtherincludes any form of dsRNA (proteolytically cleaved products of largerdsRNA, partially purified RNA, essentially pure RNA, synthetic RNA,recombinantly produced RNA) as well as altered RNA that differs fromnaturally occurring RNA by the addition, deletion, substitution, and/oralteration of one or more nucleotides.

As used herein, the term “solid support” relates to a solvent insolublesubstrate that is capable of forming linkages (e.g., covalent bonds)with various compounds. The support can be either biological in nature,such as, without limitation, a cell or bacteriophage particle, orsynthetic, such as, without limitation, an acrylamide derivative,agarose, cellulose, nylon, silica, or magnetized particles.

By the term “specifically binds to”, as used herein, is meant when acompound or ligand functions in a binding reaction or assay conditionswhich is determinative of the presence of the compound in a sample ofheterogeneous compounds.

The term “standard,” as used herein, refers to something used forcomparison. For example, it can be a known standard agent or compoundwhich is administered and used for comparing results when administeringa test compound, or it can be a standard parameter or function which ismeasured to obtain a control value when measuring an effect of an agentor compound on a parameter or function. “Standard” can also refer to an“internal standard”, such as an agent or compound which is added atknown amounts to a sample and which is useful in determining such thingsas purification or recovery rates when a sample is processed orsubjected to purification or extraction procedures before a marker ofinterest is measured. Internal standards are often but are not limitedto, a purified marker of interest which has been labeled, such as with aradioactive isotope, allowing it to be distinguished from an endogenoussubstance in a sample.

The term “stimulate” as used herein, means to induce or increase anactivity or function level such that it is higher relative to a controlvalue. The stimulation can be via direct or indirect mechanisms. In oneaspect, the activity or function is stimulated by at least 10% comparedto a control value, including by at least 25%, including by at least50%. The term “stimulator” as used herein, refers to any composition,compound or agent, the application of which results in the stimulationof a process or function of interest, including, but not limited to,wound healing, angiogenesis, bone healing, osteoblast production andfunction, and osteoclast production, differentiation, and activity.

A “subject” of analysis, diagnosis, or treatment is an animal. Suchanimals include mammals, such as a human.

As used herein, a “subject in need thereof” is a patient, animal,mammal, or human, who will benefit from the method of this invention.

As used herein, a “substantially homologous amino acid sequences”includes those amino acid sequences which have at least about 95%homology, including at least about 96% homology, including at leastabout 97% homology, including at least about 98% homology, and includingat least about 99% or more homology to an amino acid sequence of areference antibody chain. Amino acid sequence similarity or identity canbe computed by using the BLASTP and TBLASTN programs which employ theBLAST (basic local alignment search tool) 2.0.14 algorithm. The defaultsettings used for these programs are suitable for identifyingsubstantially similar amino acid sequences for purposes of the presentinvention.

“Substantially homologous nucleic acid sequence” means a nucleic acidsequence corresponding to a reference nucleic acid sequence wherein thecorresponding sequence encodes a peptide having substantially the samestructure and function as the peptide encoded by the reference nucleicacid sequence; e.g., where only changes in amino acids not significantlyaffecting the peptide function occur. In one embodiment, thesubstantially identical nucleic acid sequence encodes the peptideencoded by the reference nucleic acid sequence. The percentage ofidentity between the substantially similar nucleic acid sequence and thereference nucleic acid sequence is at least about 50%, 65%, 75%, 85%,95%, 99% or more. Substantial identity of nucleic acid sequences can bedetermined by comparing the sequence identity of two sequences, forexample by physical/chemical methods (i.e., hybridization) or bysequence alignment via computer algorithm. Suitable nucleic acidhybridization conditions to determine if a nucleotide sequence issubstantially similar to a reference nucleotide sequence are: 7% sodiumdodecyl sulfate SDS, 0.5 M NaPO₄, 1 mM EDTA at 50° C. with washing in 2×standard saline citrate (SSC), 0.1% SDS at 50° C.; such as in 7% (SDS),0.5 M NaPO₄, 1 mM EDTA at 50° C. with washing in 1×SSC, 0.1% SDS at 50°C.; such as 7% SDS, 0.5 M NaPO₄, 1 mM EDTA at 50° C. with washing in0.5×SSC, 0.1% SDS at 50° C.; including in 7% SDS, 0.5 M NaPO₄, 1 mM EDTAat 50° C. with washing in 0.1×SSC, 0.1% SDS at 65° C. Suitable computeralgorithms to determine substantial similarity between two nucleic acidsequences include, GCS program package (Devereux et al., 1984 Nucl.Acids Res. 12:387), and the BLASTN or FASTA programs (Altschul et al.,1990 Proc. Natl. Acad. Sci. USA. 1990 87:14:5509-13; Altschul et al., J.Mol. Biol. 1990 215:3:403-10; Altschul et al., 1997 Nucleic Acids Res.25:3389-3402). The default settings provided with these programs aresuitable for determining substantial similarity of nucleic acidsequences for purposes of the present invention.

The term “substantially pure” describes a compound, e.g., a protein orpolypeptide that has been separated from components which naturallyaccompany it. Typically, a compound is substantially pure when at least10%, including at least 20%, including at least 50%, including at least60%, including at least 75%, including at least 90%, and including atleast 99% of the total material (by volume, by wet or dry weight, or bymole percent or mole fraction) in a sample is the compound of interest.Purity can be measured by any appropriate method, e.g., in the case ofpolypeptides by column chromatography, gel electrophoresis, or HPLCanalysis. A compound, e.g., a protein, is also substantially purifiedwhen it is essentially free of naturally associated components or whenit is separated from the native contaminants which accompany it in itsnatural state.

The term “symptom,” as used herein, refers to any morbid phenomenon ordeparture from the normal in structure, function, or sensation,experienced by the patient and indicative of disease. In contrast, a“sign” is objective evidence of disease. For example, a bloody nose is asign. It is evident to the patient, doctor, nurse and other observers.

As used herein, the term “treating” can include prophylaxis of thespecific disorder or condition, or alleviation of the symptomsassociated with a specific disorder or condition and/or preventing oreliminating said symptoms. A “prophylactic” treatment is a treatmentadministered to a subject who does not exhibit signs of a disease orexhibits only early signs of the disease for the purpose of decreasingthe risk of developing pathology associated with the disease.

A “therapeutic” treatment is a treatment administered to a subject whoexhibits signs of pathology for the purpose of diminishing oreliminating those signs.

A “therapeutically effective amount” of a compound is that amount ofcompound which is sufficient to provide a beneficial effect to thesubject to which the compound is administered.

The term to “treat,” as used herein, means reducing the frequency withwhich symptoms are experienced by a patient or subject or administeringan agent or compound to reduce the frequency with which symptoms areexperienced.

A “vector” is a composition of matter which comprises an isolatednucleic acid and which can be used to deliver the isolated nucleic acidto the interior of a cell. Numerous vectors are known in the artincluding, but not limited to, linear polynucleotides, polynucleotidesassociated with ionic or amphiphilic compounds, plasmids, and viruses.Thus, the term “vector” includes an autonomously replicating plasmid ora virus. The term should also be construed to include non-plasmid andnon-viral compounds which facilitate transfer or delivery of nucleicacid to cells, such as, for example, polylysine compounds, liposomes,and the like. Examples of viral vectors include, but are not limited to,adenoviral vectors, adeno-associated virus vectors, retroviral vectors,recombinant viral vectors, and the like. Examples of non-viral vectorsinclude, but are not limited to, liposomes, polyamine derivatives of DNAand the like.

“Expression vector” refers to a vector comprising a recombinantpolynucleotide comprising expression control sequences operativelylinked to a nucleotide sequence to be expressed. An expression vectorcomprises sufficient cis-acting elements for expression; other elementsfor expression can be supplied by the host cell or in an in vitroexpression system. Expression vectors include all those known in theart, such as cosmids, plasmids (e.g., naked or contained in liposomes)and viruses that incorporate the recombinant polynucleotide.

Embodiments

Peptide Modification and Preparation

Peptide preparation is described in the Examples. It will beappreciated, of course, that the proteins or peptides of the inventionmay incorporate amino acid residues which are modified without affectingactivity. For example, the termini may be derivatized to includeblocking groups, i.e. chemical substituents suitable to protect and/orstabilize the N- and C-termini from “undesirable degradation”, a termmeant to encompass any type of enzymatic, chemical or biochemicalbreakdown of the compound at its termini which is likely to affect thefunction of the compound, i.e. sequential degradation of the compound ata terminal end thereof.

Blocking groups include protecting groups conventionally used in the artof peptide chemistry which will not adversely affect the in vivoactivities of the peptide. For example, suitable N-terminal blockinggroups can be introduced by alkylation or acylation of the N-terminus.Examples of suitable N-terminal blocking groups include C₁-C₅ branchedor unbranched alkyl groups, acyl groups such as formyl and acetylgroups, as well as substituted forms thereof, such as theacetamidomethyl (Acm) group. Desamino analogs of amino acids are alsouseful N-terminal blocking groups, and can either be coupled to theN-terminus of the peptide or used in place of the N-terminal reside.Suitable C-terminal blocking groups, in which the carboxyl group of theC-terminus is either incorporated or not, include esters, ketones oramides. Ester or ketone-forming alkyl groups, particularly lower alkylgroups such as methyl, ethyl and propyl, and amide-forming amino groupssuch as primary amines (—NH₂), and mono- and di-alkylamino groups suchas methylamino, ethylamino, dimethylamino, diethylamino,methylethylamino and the like are examples of C-terminal blockinggroups. Descarboxylated amino acid analogues such as agmatine are alsouseful C-terminal blocking groups and can be either coupled to thepeptide's C-terminal residue or used in place of it. Further, it will beappreciated that the free amino and carboxyl groups at the termini canbe removed altogether from the peptide to yield desamino anddescarboxylated forms thereof without affect on peptide activity.

Acid addition salts of the present invention are also contemplated asfunctional equivalents. Thus, a peptide in accordance with the presentinvention treated with an inorganic acid such as hydrochloric,hydrobromic, sulfuric, nitric, phosphoric, and the like, or an organicacid such as an acetic, propionic, glycolic, pyruvic, oxalic, malic,malonic, succinic, maleic, fumaric, tataric, citric, benzoic, cinnamie,mandelic, methanesulfonic, ethanesulfonic, p-toluenesulfonic, salicyclicand the like, to provide a water soluble salt of the peptide is suitablefor use in the invention.

Modifications (which do not normally alter primary sequence) include invivo, or in vitro chemical derivatization of polypeptides, e.g.,acetylation, or carboxylation. Also included are modifications ofglycosylation, e.g., those made by modifying the glycosylation patternsof a polypeptide during its synthesis and processing or in furtherprocessing steps; e.g., by exposing the polypeptide to enzymes whichaffect glycosylation, e.g., mammalian glycosylating or deglycosylatingenzymes. Also embraced are sequences which have phosphorylated aminoacid residues, e.g., phosphotyrosine, phosphoserine, orphosphothreonine.

Also included are polypeptides which have been modified using ordinarymolecular biological techniques so as to improve their resistance toproteolytic degradation or to optimize solubility properties or torender them more suitable as a therapeutic agent. Analogs of suchpolypeptides include those containing residues other than naturallyoccurring L-amino acids, e.g., D-amino acids or non-naturally occurringor non-standard synthetic amino acids. The peptides of the invention arenot limited to products of any of the specific exemplary processeslisted herein.

The invention includes the use of beta-alanine (also referred to asβ-alanine, β-Ala, bA, and βA, having the structure:

Sequences are provided herein which use the symbol “βA”, but in aSequence Listing “βA” can be provided as “Xaa” and reference in the textof the Sequence Listing indicates that Xaa is beta alanine.

Peptides useful in the present invention, such as standards, ormodifications for analysis, may be readily prepared by standard,well-established techniques, such as solid-phase peptide synthesis(SPPS) as described by Stewart et al. in Solid Phase Peptide Synthesis,2nd Edition, 1984, Pierce Chemical Company, Rockford, Ill.; and asdescribed by Bodanszky and Bodanszky in The Practice of PeptideSynthesis, 1984, Springer-Verlag, New York. At the outset, a suitablyprotected amino acid residue is attached through its carboxyl group to aderivatized, insoluble polymeric support, such as cross-linkedpolystyrene or polyamide resin. “Suitably protected” refers to thepresence of protecting groups on both the α-amino group of the aminoacid, and on any side chain functional groups. Side chain protectinggroups are generally stable to the solvents, reagents and reactionconditions used throughout the synthesis, and are removable underconditions which will not affect the final peptide product. Stepwisesynthesis of the oligopeptide is carried out by the removal of theN-protecting group from the initial amino acid, and couple thereto ofthe carboxyl end of the next amino acid in the sequence of the desiredpeptide. This amino acid is also suitably protected. The carboxyl of theincoming amino acid can be activated to react with the N-terminus of thesupport-bound amino acid by formation into a reactive group such asformation into a carbodiimide, a symmetric acid anhydride or an “activeester” group such as hydroxybenzotriazole or pentafluorophenyl esters.

Examples of solid phase peptide synthesis methods include the BOC methodwhich utilized tert-butyloxcarbonyl as the α-amino protecting group, andthe FMOC method which utilizes 9-fluorenylmethyloxcarbonyl to protectthe α-amino of the amino acid residues, both methods of which arewell-known by those of skill in the art.

Incorporation of N- and/or C-blocking groups can also be achieved usingprotocols conventional to solid phase peptide synthesis methods. Forincorporation of C-terminal blocking groups, for example, synthesis ofthe desired peptide is typically performed using, as solid phase, asupporting resin that has been chemically modified so that cleavage fromthe resin results in a peptide having the desired C-terminal blockinggroup. To provide peptides in which the C-terminus bears a primary aminoblocking group, for instance, synthesis is performed using ap-methylbenzhydrylamine (MBHA) resin so that, when peptide synthesis iscompleted, treatment with hydrofluoric acid releases the desiredC-terminally amidated peptide. Similarly, incorporation of anN-methylamine blocking group at the C-terminus is achieved usingN-methylaminoethyl-derivatized DVB, resin, which upon HF treatmentreleases a peptide bearing an N-methylamidated C-terminus. Blockage ofthe C-terminus by esterification can also be achieved using conventionalprocedures. This entails use of resin/blocking group combination thatpermits release of side-chain peptide from the resin, to allow forsubsequent reaction with the desired alcohol, to form the esterfunction. FMOC protecting group, in combination with DVB resinderivatized with methoxyalkoxybenzyl alcohol or equivalent linker, canbe used for this purpose, with cleavage from the support being affectedby TFA in dicholoromethane. Esterification of the suitably activatedcarboxyl function e.g. with DCC, can then proceed by addition of thedesired alcohol, followed by deprotection and isolation of theesterified peptide product.

Incorporation of N-terminal blocking groups can be achieved while thesynthesized peptide is still attached to the resin, for instance bytreatment with a suitable anhydride and nitrile. To incorporate anacetyl blocking group at the N-terminus, for instance, the resin-coupledpeptide can be treated with 20% acetic anhydride in acetonitrile. TheN-blocked peptide product can then be cleaved from the resin,deprotected and subsequently isolated.

To ensure that the peptide obtained from either chemical or biologicalsynthetic techniques is the desired peptide, analysis of the peptidecomposition should be conducted. Such amino acid composition analysismay be conducted using high resolution mass spectrometry to determinethe molecular weight of the peptide. Alternatively, or additionally, theamino acid content of the peptide can be confirmed by hydrolyzing thepeptide in aqueous acid, and separating, identifying and quantifying thecomponents of the mixture using HPLC, or an amino acid analyzer. Proteinsequenators, which sequentially degrade the peptide and identify theamino acids in order, may also be used to determine definitely thesequence of the peptide.

Prior to its use, the peptide may be purified to remove contaminants. Inthis regard, it will be appreciated that the peptide will be purified soas to meet the standards set out by the appropriate regulatory agencies.Any one of a number of a conventional purification procedures may beused to attain the required level of purity including, for example,reversed-phase high performance liquid chromatography (HPLC) using analkylated silica column such as C₄-, C₈- or C₁₈-silica. A gradientmobile phase of increasing organic content is generally used to achievepurification, for example, acetonitrile in an aqueous buffer, usuallycontaining a small amount of trifluoroacetic acid. Ion-exchangechromatography can be also used to separate peptides based on theircharge.

Substantially pure protein obtained as described herein may be purifiedby following known procedures for protein purification, wherein animmunological, enzymatic or other assay is used to monitor purificationat each stage in the procedure. Protein purification methods are wellknown in the art, and are described, for example in Deutscher et al.(ed., 1990, Guide to Protein Purification, Harcourt Brace Jovanovich,San Diego).

As discussed, modifications or optimizations of peptide ligands of theinvention are within the scope of the application. Modified or optimizedpeptides are included within the definition of peptide binding ligand.Specifically, a peptide sequence identified can be modified to optimizeits potency, pharmacokinetic behavior, stability and/or otherbiological, physical and chemical properties.

Amino Acid Substitutions

In certain embodiments, the disclosed methods and compositions mayinvolve preparing peptides with one or more substituted amino acidresidues.

In various embodiments, the structural, physical and/or therapeuticcharacteristics of peptide sequences may be optimized by replacing oneor more amino acid residues.

Other modifications can also be incorporated without adversely affectingthe activity and these include, but are not limited to, substitution ofone or more of the amino acids in the natural L-isomeric form with aminoacids in the D-isomeric form. Thus, the peptide may include one or moreD-amino acid resides, or may comprise amino acids which are all in theD-form. Retro-inverso forms of peptides in accordance with the presentinvention are also contemplated, for example, inverted peptides in whichall amino acids are substituted with D-amino acid forms.

The skilled artisan will be aware that, in general, amino acidsubstitutions in a peptide typically involve the replacement of an aminoacid with another amino acid of relatively similar properties (i.e.,conservative amino acid substitutions). The properties of the variousamino acids and effect of amino acid substitution on protein structureand function have been the subject of extensive study and knowledge inthe art.

For example, one can make the following isosteric and/or conservativeamino acid changes in the parent polypeptide sequence with theexpectation that the resulting polypeptides would have a similar orimproved profile of the properties described above:

Substitution of alkyl-substituted hydrophobic amino acids: includingalanine, leucine, isoleucine, valine, norleucine, S-2-aminobutyric acid,S-cyclohexylalanine or other simple alpha-amino acids substituted by analiphatic side chain from C1-10 carbons including branched, cyclic andstraight chain alkyl, alkenyl or alkynyl substitutions.

Substitution of aromatic-substituted hydrophobic amino acids: includingphenylalanine, tryptophan, tyrosine, biphenylalanine, 1-naphthylalanine,2-naphthylalanine, 2-benzothienylalanine, 3-benzothienylalanine,histidine, amino, alkylamino, dialkylamino, aza, halogenated (fluoro,chloro, bromo, or iodo) or alkoxy-substituted forms of the previouslisted aromatic amino acids, illustrative examples of which are: 2-,3-or 4-aminophenylalanine, 2-,3- or 4-chlorophenylalanine, 2-,3- or4-methylphenylalanine, 2-,3- or 4-methoxyphenylalanine, 5-amino-,5-chloro-, 5-methyl- or 5-methoxytryptophan, 2′-, 3′-, or 4′-amino-,2′-, 3′-, or 4′-chloro-, 2,3, or 4-biphenylalanine, 2′,-3′,- or4′-methyl-2, 3 or 4-biphenylalanine, and 2- or 3-pyridylalanine.

Substitution of amino acids containing basic functions: includingarginine, lysine, histidine, ornithine, 2,3-diaminopropionic acid,homoarginine, alkyl, alkenyl, or aryl-substituted (from C₁-C₁₀ branched,linear, or cyclic) derivatives of the previous amino acids, whether thesubstituent is on the heteroatoms (such as the alpha nitrogen, or thedistal nitrogen or nitrogens, or on the alpha carbon, in the pro-Rposition for example. Compounds that serve as illustrative examplesinclude: N-epsilon-isopropyl-lysine, 3-(4-tetrahydropyridyl)-glycine,3-(4-tetrahydropyridyl)-alanine, N,N-gamma, gamma′-diethyl-homoarginine.Included also are compounds such as alpha methyl arginine, alpha methyl2,3-diaminopropionic acid, alpha methyl histidine, alpha methylornithine where alkyl group occupies the pro-R position of the alphacarbon. Also included are the amides formed from alkyl, aromatic,heteroaromatic (where the heteroaromatic group has one or morenitrogens, oxygens, or sulfur atoms singly or in combination) carboxylicacids or any of the many well-known activated derivatives such as acidchlorides, active esters, active azolides and related derivatives) andlysine, ornithine, or 2,3-diaminopropionic acid.

Substitution of acidic amino acids: including aspartic acid, glutamicacid, homoglutamic acid, tyrosine, alkyl, aryl, arylalkyl, andheteroaryl sulfonamides of 2,4-diaminopriopionic acid, ornithine orlysine and tetrazole-substituted alkyl amino acids.

Substitution of side chain amide residues: including asparagine,glutamine, and alkyl or aromatic substituted derivatives of asparagineor glutamine.

Substitution of hydroxyl containing amino acids: including serine,threonine, homoserine, 2,3-diaminopropionic acid, and alkyl or aromaticsubstituted derivatives of serine or threonine. It is also understoodthat the amino acids within each of the categories listed above can besubstituted for another of the same group.

For example, the hydropathic index of amino acids may be considered(Kyte & Doolittle, 1982, J. Mol. Biol., 157:105-132). The relativehydropathic character of the amino acid contributes to the secondarystructure of the resultant protein, which in turn defines theinteraction of the protein with other molecules. Each amino acid hasbeen assigned a hydropathic index on the basis of its hydrophobicity andcharge characteristics (Kyte & Doolittle, 1982), these are: isoleucine(+4.5); valine (+4.2); leucine (+3.8); phenylalanine (+2.8);cysteine/cystine (+2.5); methionine (+1.9); alanine (+1.8); glycine(−0.4); threonine (−0.7); serine (−0.8); tryptophan (−0.9); tyrosine(−1.3); proline (−1.6); histidine (−3.2); glutamate (−3.5); glutamine(−3.5); aspartate (−3.5); asparagine (−3.5); lysine (−3.9); and arginine(−4.5). In making conservative substitutions, the use of amino acidswhose hydropathic indices are within +/−2, within +/−1, and within+/−0.5 are included in an embodiment.

Amino acid substitution may also take into account the hydrophilicity ofthe amino acid residue (e.g., U.S. Pat. No. 4,554,101). Hydrophilicityvalues have been assigned to amino acid residues: arginine (+3.0);lysine (+3.0); aspartate (+3.0); glutamate (+3.0); serine (+0.3);asparagine (+0.2); glutamine (+0.2); glycine (0); threonine (−0.4);proline (−0.5.+−0.1); alanine (−0.5); histidine (−0.5); cysteine (−1.0);methionine (−1.3); valine (−1.5); leucine (−1.8); isoleucine (−1.8);tyrosine (−2.3); phenylalanine (−2.5); tryptophan (−3.4). Replacement ofamino acids with others of similar hydrophilicity is provided in oneembodiment.

Other considerations include the size of the amino acid side chain. Forexample, it would generally not be desired to replace an amino acid witha compact side chain, such as glycine or serine, with an amino acid witha bulky side chain, e.g., tryptophan or tyrosine. The effect of variousamino acid residues on protein secondary structure is also aconsideration. Through empirical study, the effect of different aminoacid residues on the tendency of protein domains to adopt analpha-helical, beta-sheet or reverse turn secondary structure has beendetermined and is known in the art (see, e.g., Chou & Fasman, 1974,Biochemistry, 13:222-245; 1978, Ann. Rev. Biochem., 47: 251-276; 1979,Biophys. J., 26:367-384).

Based on such considerations and extensive empirical study, tables ofconservative amino acid substitutions have been constructed and areknown in the art. For example: arginine and lysine; glutamate andaspartate; serine and threonine; glutamine and asparagine; and valine,leucine and isoleucine. Alternatively: Ala (A) leu, ile, val; Arg (R)gln, asn, lys; Asn (N) his, asp, lys, arg, gln; Asp (D) asn, glu; Cys(C) ala, ser; Gln (Q) glu, asn; Glu (E) gln, asp; Gly (G) ala; His (H)asn, gln, lys, arg; Ile (I) val, met, ala, phe, leu; Leu (L) val, met,ala, phe, ile; Lys (K) gln, asn, arg; Met (M) phe, ile, leu; Phe (F)leu, val, ile, ala, tyr; Pro (P) ala; Ser (S), thr; Thr (T) ser; Trp (W)phe, tyr; Tyr (Y) trp, phe, thr, ser; Val (V) ile, leu, met, phe, ala.

Other considerations for amino acid substitutions include whether or notthe residue is located in the interior of a protein or is solventexposed. For interior residues, conservative substitutions wouldinclude: Asp and Asn; Ser and Thr; Ser and Ala; Thr and Ala; Ala andGly; Ile and Val; Val and Leu; Leu and Ile; Leu and Met; Phe and Tyr;Tyr and Trp. (See, e.g., PROWL Rockefeller University website). Forsolvent exposed residues, conservative substitutions would include: Aspand Asn; Asp and Glu; Glu and Gln; Glu and Ala; Gly and Asn; Ala andPro; Ala and Gly; Ala and Ser; Ala and Lys; Ser and Thr; Lys and Arg;Val and Leu; Leu and Ile; Ile and Val; Phe and Tyr. (Id.) Variousmatrices have been constructed to assist in selection of amino acidsubstitutions, such as the PAM250 scoring matrix, Dayhoff matrix,Grantham matrix, McLachlan matrix, Doolittle matrix, Henikoff matrix,Miyata matrix, Fitch matrix, Jones matrix, Rao matrix, Levin matrix andRisler matrix (Idem.)

In determining amino acid substitutions, one may also consider theexistence of intermolecular or intramolecular bonds, such as formationof ionic bonds (salt bridges) between positively charged residues (e.g.,His, Arg, Lys) and negatively charged residues (e.g., Asp, Glu) ordisulfide bonds between nearby cysteine residues.

Methods of substituting any amino acid for any other amino acid in anencoded peptide sequence are well known and a matter of routineexperimentation for the skilled artisan, for example by the technique ofsite-directed mutagenesis or by synthesis and assembly ofoligonucleotides encoding an amino acid substitution and splicing intoan expression vector construct.

Linkers

Additionally, modifications encompassed by the invention includeintroduction of linkers or spacers between the targeting sequence of thebinding moiety or binding polypeptide and the detectable label ortherapeutic agent. For example, use of such linkers/spacers can improvethe relevant properties of the binding peptides (e.g., increase serumstability, etc.). These linkers can include, but are not restricted to,substituted or unsubstituted alkyl chains, polyethylene glycolderivatives, amino acid spacers, sugars, or aliphatic or aromaticspacers common in the art.

For example, suitable linkers include homobifunctional andheterobifunctional cross-linking molecules. The homobifunctionalmolecules have at least two reactive functional groups, which are thesame. The reactive functional groups on a homobifunctional moleculeinclude, for example, aldehyde groups and active ester groups.Homobifunctional molecules having aldehyde groups include, for example,glutaraldehyde and subaraldehyde.

Homobifunctional linker molecules having at least two active ester unitsinclude esters of dicarboxylic acids and N-hydroxysuccinimide. Someexamples of such N-succinimidyl esters include disuccinimidyl suberateand dithio-bis-(succinimidyl propionate), and their soluble bis-sulfonicacid and bis-sulfonate salts such as their sodium and potassium salts.

Heterobifunctional linker molecules have at least two different reactivegroups. Some examples of heterobifunctional reagents containing reactivedisulfide bonds include N-succinimidyl 3-(2-pyridyl-dithio)propionate(Carlsson et al., 1978. Biochem. J., 173:723-737), sodiumS-4-succinimidyloxycarbonyl-alpha-methylbenzylthiosulfate, and4-succinimidyloxycarbonyl-alpha-methyl-(2-pyridyldithio)toluene.N-succinimidyl 3-(2-pyridyldithio)propionate is provided in oneembodiment. Some examples of heterobifunctional reagents comprisingreactive groups having a double bond that reacts with a thiol groupinclude succinimidyl 4-(N-maleimidomethyl)cyclohexahe-1-carboxylate andsuccinimidyl m-maleimidobenzoate. Other heterobifunctional moleculesinclude succinimidyl 3-(maleimido)propionate, sulfosuccinimidyl4-(p-maleimido-phenyl)butyrate, sulfosuccinimidyl4-(N-maleimidomethyl-cyclohexane)-1-carboxylate,maleimidobenzoyl-5N-hydroxy-succinimide ester.

Furthermore, linkers that are combinations of the molecules and/ormoieties described above, can also be employed to confer specialadvantage to the properties of the peptide. Lipid molecules with linkersmay be attached to allow formulation of ultrasound bubbles, liposomes orother aggregation based constructs. Such constructs could be employed asagents for targeting and delivery of a diagnostic reporter, atherapeutic agent (e.g., a chemical “warhead” for therapy), or acombination of these.

Constructs employing dimers, multimers, or polymers of one or morepeptide ligands of the invention are also contemplated. Indeed, there isample literature evidence that the binding of low potency peptides orsmall molecules can be substantially increased by the formation ofdimers and multimers. Thus, dimeric and multimeric constructs (bothhomogeneous and heterogeneous) are within the scope of the instantinvention. The polypeptide sequences in the dimeric constructs can beattached at their N- or C-terminus or the N-epsilon nitrogen of asuitably placed lysine moiety (or another function bearing a selectivelyderivatizable group such as a pendant oxyamino or other nucleophilicgroup), or can be joined together via one or more linkers (e.g., thosediscussed herein) employing the appropriate attachment chemistry. Thiscoupling chemistry can include amide, urea, thiourea, oxime, oraminoacetylamide (from chloro- or bromoacetamide derivatives, but is notso limited). For example, methods to prepare dimeric or multimericconstructs of Plec1 binding polypeptides of the invention include atleast those discussed below.

Linkers can also be used for attachment to a chelating agent.

Therapeutic Agents

In other embodiments, therapeutic agents, including, but not limited to,cytotoxic agents, anti-angiogenic agents, pro-apoptotic agents,antibiotics, hormones, hormone antagonists, chemokines, drugs, prodrugs,toxins, enzymes or other agents may be used as adjunct therapies whenusing the agents described herein. Drugs useful in the invention may,for example, possess a pharmaceutical property selected from the groupconsisting of antimitotic, antikinase, alkylating, antimetabolite,antibiotic, alkaloid, anti-angiogenic, pro-apoptotic agents andcombinations thereof.

Nucleic acids useful in the present invention include, by way of exampleand not limitation, oligonucleotides and polynucleotides such asantisense DNAs and/or RNAs; ribozymes; DNA for gene therapy; viralfragments including viral DNA and/or RNA; DNA and/or RNA chimeras; mRNA;plasmids; cosmids; genomic DNA; cDNA; gene fragments; various structuralforms of DNA including single-stranded DNA, double-stranded DNA,supercoiled DNA and/or triple-helical DNA; Z-DNA; and the like. Thenucleic acids may be prepared by any conventional means typically usedto prepare nucleic acids in large quantity. For example, DNAs and RNAsmay be chemically synthesized using commercially available reagents andsynthesizers by methods that are well-known in the art (see, e.g., Gait,1985, OLIGONUCLEOTIDE SYNTHESIS: A PRACTICAL APPROACH (IRL Press,Oxford, England)). RNAs may be produce in high yield via in vitrotranscription using plasmids such as SP65 (Promega Corporation, Madison,Wis.).

Antibodies and their Preparation

Antibodies directed against proteins, polypeptides, or peptide fragmentsthereof of the invention may be generated using methods that are wellknown in the art. For instance, U.S. patent application Ser. No.07/481,491, which is incorporated by reference herein in its entirety,discloses methods of raising antibodies to peptides. For the productionof antibodies, various host animals, including but not limited torabbits, mice, and rats, can be immunized by injection with apolypeptide or peptide fragment thereof. To increase the immunologicalresponse, various adjuvants may be used depending on the host species,including but not limited to Freund's (complete and incomplete), mineralgels such as aluminum hydroxide, surface active substances such aslysolecithin, pluronic polyols, polyanions, peptides, oil emulsions,keyhole limpet hemocyanins, dinitrophenol, and potentially useful humanadjuvants such as BCG (bacille Calmette-Guerin) and corynebacteriumparvum.

For the preparation of monoclonal antibodies, any technique whichprovides for the production of antibody molecules by continuous celllines in culture may be utilized. For example, the hybridoma techniqueoriginally developed by Kohler and Milstein (1975, Nature 256:495-497),the trioma technique, the human B-cell hybridoma technique (Kozbor etal., 1983, Immunology Today 4:72), and the EBV-hybridoma technique (Coleet al., 1985, in Monoclonal Antibodies and Cancer Therapy, Alan R. Liss,Inc., pp. 77-96) may be employed to produce human monoclonal antibodies.In another embodiment, monoclonal antibodies are produced in germ-freeanimals.

In accordance with the invention, human antibodies may be used andobtained by utilizing human hybridomas (Cote et al., 1983, Proc. Natl.Acad. Sci. U.S.A. 80:2026-2030) or by transforming human B cells withEBV virus in vitro (Cole et al., 1985, in Monoclonal Antibodies andCancer Therapy, Alan R. Liss, Inc., pp. 77-96). Furthermore, techniquesdeveloped for the production of “chimeric antibodies” (Morrison et al.,1984, Proc. Natl. Acad. Sci. U.S.A. 81:6851-6855; Neuberger et al.,1984, Nature 312:604-608; Takeda et al., 1985, Nature 314:452-454) bysplicing the genes from a mouse antibody molecule specific for epitopesof SLLP polypeptides together with genes from a human antibody moleculeof appropriate biological activity can be employed; such antibodies arewithin the scope of the present invention. Once specific monoclonalantibodies have been developed, the preparation of mutants and variantsthereof by conventional techniques is also available.

In one embodiment, techniques described for the production ofsingle-chain antibodies (U.S. Pat. No. 4,946,778, incorporated byreference herein in its entirety) are adapted to produceprotein-specific single-chain antibodies. In another embodiment, thetechniques described for the construction of Fab expression libraries(Huse et al., 1989, Science 246:1275-1281) are utilized to allow rapidand easy identification of monoclonal Fab fragments possessing thedesired specificity for specific antigens, proteins, derivatives, oranalogs of the invention.

Antibody fragments which contain the idiotype of the antibody moleculecan be generated by known techniques. For example, such fragmentsinclude but are not limited to: the F(ab′)₂ fragment which can beproduced by pepsin digestion of the antibody molecule; the Fab′fragments which can be generated by reducing the disulfide bridges ofthe F(ab′)₂ fragment; the Fab fragments which can be generated bytreating the antibody molecule with papain and a reducing agent; and Fvfragments.

The generation of polyclonal antibodies is accomplished by inoculatingthe desired animal with the antigen and isolating antibodies whichspecifically bind the antigen therefrom.

Monoclonal antibodies directed against full length or peptide fragmentsof a protein or peptide may be prepared using any well known monoclonalantibody preparation procedures, such as those described, for example,in Harlow et al. (1988, In: Antibodies, A Laboratory Manual, Cold SpringHarbor, N.Y.) and in Tuszynski et al. (1988, Blood, 72:109-115).Quantities of the desired peptide may also be synthesized using chemicalsynthesis technology. Alternatively, DNA encoding the desired peptidemay be cloned and expressed from an appropriate promoter sequence incells suitable for the generation of large quantities of peptide.Monoclonal antibodies directed against the peptide are generated frommice immunized with the peptide using standard procedures as referencedherein.

A nucleic acid encoding the monoclonal antibody obtained using theprocedures described herein may be cloned and sequenced using technologywhich is available in the art, and is described, for example, in Wrightet al. (1992, Critical Rev. in Immunol. 12(3,4):125-168) and thereferences cited therein. Further, the antibody of the invention may be“humanized” using the technology described in Wright et al., (supra) andin the references cited therein, and in Gu et al. (1997, Thrombosis andHematocyst 77(4):755-759).

To generate a phage antibody library, a cDNA library is first obtainedfrom mRNA which is isolated from cells, e.g., the hybridoma, whichexpress the desired protein to be expressed on the phage surface, e.g.,the desired antibody. cDNA copies of the mRNA are produced using reversetranscriptase. cDNA which specifies immunoglobulin fragments areobtained by PCR and the resulting DNA is cloned into a suitablebacteriophage vector to generate a bacteriophage DNA library comprisingDNA specifying immunoglobulin genes. The procedures for making abacteriophage library comprising heterologous DNA are well known in theart and are described, for example, in Sambrook et al. (1989, MolecularCloning: A Laboratory Manual, Cold Spring Harbor, N.Y.).

Bacteriophage which encode the desired antibody, may be engineered suchthat the protein is displayed on the surface thereof in such a mannerthat it is available for binding to its corresponding binding protein,e.g., the antigen against which the antibody is directed. Thus, whenbacteriophage which express a specific antibody are incubated in thepresence of a cell which expresses the corresponding antigen, thebacteriophage will bind to the cell. Bacteriophage which do not expressthe antibody will not bind to the cell. Such panning techniques are wellknown in the art.

Processes such as those described above, have been developed for theproduction of human antibodies using M13 bacteriophage display (Burtonet al., 1994, Adv. Immunol. 57:191-280). Essentially, a cDNA library isgenerated from mRNA obtained from a population of antibody-producingcells. The mRNA encodes rearranged immunoglobulin genes and thus, thecDNA encodes the same. Amplified cDNA is cloned into M13 expressionvectors creating a library of phage which express human Fab fragments ontheir surface. Phage which display the antibody of interest are selectedby antigen binding and are propagated in bacteria to produce solublehuman Fab immunoglobulin. Thus, in contrast to conventional monoclonalantibody synthesis, this procedure immortalizes DNA encoding humanimmunoglobulin rather than cells which express human immunoglobulin.

The procedures just presented describe the generation of phage whichencode the Fab portion of an antibody molecule. However, the inventionshould not be construed to be limited solely to the generation of phageencoding Fab antibodies. Rather, phage which encode single chainantibodies (scFv/phage antibody libraries) are also included in theinvention. Fab molecules comprise the entire Ig light chain, that is,they comprise both the variable and constant region of the light chain,but include only the variable region and first constant region domain(CH1) of the heavy chain. Single chain antibody molecules comprise asingle chain of protein comprising the Ig Fv fragment. An Ig Fv fragmentincludes only the variable regions of the heavy and light chains of theantibody, having no constant region contained therein. Phage librariescomprising scFv DNA may be generated following the procedures describedin Marks et al., 1991, J. Mol. Biol. 222:581-597. Panning of phage sogenerated for the isolation of a desired antibody is conducted in amanner similar to that described for phage libraries comprising Fab DNA.

The invention should also be construed to include synthetic phagedisplay libraries in which the heavy and light chain variable regionsmay be synthesized such that they include nearly all possiblespecificities (Barbas, 1995, Nature Medicine 1:837-839; de Kruif et al.1995, J. Mol. Biol. 248:97-105).

In the production of antibodies, screening for the desired antibody canbe accomplished by techniques known in the art, e.g., ELISA(enzyme-linked immunosorbent assay). Antibodies generated in accordancewith the present invention may include, but are not limited to,polyclonal, monoclonal, chimeric (i.e., “humanized”), and single chain(recombinant) antibodies, Fab fragments, and fragments produced by a Fabexpression library.

Aptamers

The present invention is also directed to useful aptamers. In oneembodiment, an aptamer is a compound that is selected in vitro to bindpreferentially to another compound (in this case the identifiedproteins). In one aspect, aptamers are nucleic acids or peptides,because random sequences can be readily generated from nucleotides oramino acids (both naturally occurring or synthetically made) in largenumbers but of course they need not be limited to these. In anotheraspect, the nucleic acid aptamers are short strands of DNA that bindprotein targets. In one aspect, the aptamers are oligonucleotideaptamers. Oligonucleotide aptamers are oligonucleotides which can bindto a specific protein sequence of interest. A general method ofidentifying aptamers is to start with partially degenerateoligonucleotides, and then simultaneously screen the many thousands ofoligonucleotides for the ability to bind to a desired protein. The boundoligonucleotide can be eluted from the protein and sequenced to identifythe specific recognition sequence. Transfer of large amounts of achemically stabilized aptamer into cells can result in specific bindingto a polypeptide of interest, thereby blocking its function. [Forexample, see the following publications describing in vitro selection ofaptamers: Klug et al., Mol. Biol. Reports 20:97-107 (1994); Wallis etal., Chem. Biol. 2:543-552 (1995); Ellington, Curr. Biol. 4:427-429(1994); Lato et al., Chem. Biol. 2:291-303 (1995); Conrad et al., Mol.Div. 1:69-78 (1995); and Uphoff et al., Curr. Opin. Struct. Biol.6:281-287 (1996)].

Aptamers offer advantages over other oligonucleotide-based approachesthat artificially interfere with target gene function due to theirability to bind protein products of these genes with high affinity andspecificity. However, RNA aptamers can be limited in their ability totarget intracellular proteins since even nuclease-resistant aptamers donot efficiently enter the intracellular compartments. Moreover, attemptsat expressing RNA aptamers within mammalian cells through vector-basedapproaches have been hampered by the presence of additional flankingsequences in expressed RNA aptamers, which may alter their functionalconformation.

The idea of using single-stranded nucleic acids (DNA and RNA aptamers)to target protein molecules is based on the ability of short sequences(20 mers to 80 mers) to fold into unique 3D conformations that enablethem to bind targeted proteins with high affinity and specificity. RNAaptamers have been expressed successfully inside eukaryotic cells, suchas yeast and multicellular organisms, and have been shown to haveinhibitory effects on their targeted proteins in the cellularenvironment.

In binding assays, the interaction is binding and the complex formed canbe isolated or detected in the reaction mixture. In a particularembodiment, one of the peptides of the complexes described herein, orthe test compound or drug candidate is immobilized on a solid phase,e.g., on a microtiter plate, by covalent or non-covalent attachments.Non-covalent attachment generally is accomplished by coating the solidsurface with a solution of the peptide and drying. Alternatively, animmobilized antibody, e.g., a monoclonal antibody, specific for thepeptide to be immobilized can be used to anchor it to a solid surface.The assay is performed by adding the non-immobilized component, whichmay be labeled by a detectable label, to the immobilized component,e.g., the coated surface containing the anchored component. When thereaction is complete, the non-reacted components are removed, e.g., bywashing, and complexes anchored on the solid surface are detected. Whenthe originally non-immobilized component carries a detectable label, thedetection of label immobilized on the surface indicates that complexingoccurred. Where the originally non-immobilized component does not carrya label, complexing can be detected, for example, by using a labeledantibody specifically binding the immobilized complex.

The present invention also encompasses pharmaceutical and therapeuticcompositions comprising the multimeric peptide ligand complexes of thepresent invention. More particularly, such compounds can be formulatedas pharmaceutical compositions using standard pharmaceuticallyacceptable carriers, fillers, solubilizing agents and stabilizers knownto those skilled in the art.

The present invention further provides a pharmaceutical preparationcomprising one or more of the compounds, drugs, or molecules of theinvention that are active as described herein.

The concentration of compounds, drugs, or molecules in thepharmaceutical composition can vary widely, i.e., from less than about0.1% by weight, usually being at least about 1% by weight to as much as20% by weight or more.

The composition may comprise a pharmaceutically acceptable carrier inaddition to the active ingredient. The pharmaceutical carrier can be anycompatible, non-toxic substance suitable to deliver the peptides o tothe patient. For polypeptides, sterile water, alcohol, fats, waxes, andinert solids may be used as the carrier. Pharmaceutically acceptableadjuvants, buffering agents, dispersing agents, and the like, may alsobe incorporated into the pharmaceutical compositions.

Methods of producing pharmaceutical compositions comprising polypeptidesare described in U.S. Pat. Nos. 5,789,543 and 6,207,718. The form useddepends on the intended mode of administration and therapeuticapplication.

Pharmaceutical Compositions and Administration

The invention is also directed to methods of administering the compoundsof the invention to a subject.

Pharmaceutical compositions comprising the present compounds areadministered to a subject in need thereof by any number of routesincluding, but not limited to, topical, oral, intravenous,intramuscular, intra-arterial, intramedullary, intrathecal,intraventricular, transdermal, subcutaneous, intraperitoneal,intranasal, enteral, topical, sublingual, or rectal means.

In accordance with one embodiment, a method of treating a subject inneed of such treatment is provided. The method comprises administering apharmaceutical composition comprising at least one compound of thepresent invention to a subject in need thereof. Compounds identified bythe methods of the invention can be administered with known compounds orother medications as well.

The pharmaceutical compositions useful for practicing the invention maybe administered to deliver a dose of between 1 ng/kg/day and 100mg/kg/day.

The invention encompasses the preparation and use of pharmaceuticalcompositions comprising a compound useful for treatment of the diseasesdisclosed herein as an active ingredient. Such a pharmaceuticalcomposition may consist of the active ingredient alone, in a formsuitable for administration to a subject, or the pharmaceuticalcomposition may comprise the active ingredient and one or morepharmaceutically acceptable carriers, one or more additionalingredients, or some combination of these. The active ingredient may bepresent in the pharmaceutical composition in the form of aphysiologically acceptable ester or salt, such as in combination with aphysiologically acceptable cation or anion, as is well known in the art.

As used herein, the term “physiologically acceptable” ester or saltmeans an ester or salt form of the active ingredient which is compatiblewith any other ingredients of the pharmaceutical composition, which isnot deleterious to the subject to which the composition is to beadministered.

The formulations of the pharmaceutical compositions described herein maybe prepared by any method known or hereafter developed in the art ofpharmacology. In general, such preparatory methods include the step ofbringing the active ingredient into association with a carrier or one ormore other accessory ingredients, and then, if desirable, shaping orpackaging the product into a desired single- or multi-dose unit.

It will be understood by the skilled artisan that such pharmaceuticalcompositions are generally suitable for administration to animals of allsorts. Subjects to which administration of the pharmaceuticalcompositions of the invention is contemplated include, but are notlimited to, humans and other primates, mammals including commerciallyrelevant mammals such as cattle, pigs, horses, sheep, cats, and dogs,birds including commercially relevant birds such as chickens, ducks,geese, and turkeys. The invention is also contemplated for use incontraception for nuisance animals such as rodents.

A pharmaceutical composition of the invention may be prepared, packaged,or sold in bulk, as a single unit dose, or as a plurality of single unitdoses. As used herein, a “unit dose” is discrete amount of thepharmaceutical composition comprising a predetermined amount of theactive ingredient. The amount of the active ingredient is generallyequal to the dosage of the active ingredient which would be administeredto a subject or a convenient fraction of such a dosage such as, forexample, one-half or one-third of such a dosage.

The relative amounts of the active ingredient, the pharmaceuticallyacceptable carrier, and any additional ingredients in a pharmaceuticalcomposition of the invention will vary, depending upon the identity,size, and condition of the subject treated and further depending uponthe route by which the composition is to be administered. By way ofexample, the composition may comprise between 0.1% and 100% (w/w) activeingredient.

In addition to the active ingredient, a pharmaceutical composition ofthe invention may further comprise one or more additionalpharmaceutically active agents. Particularly contemplated additionalagents include anti-emetics and scavengers such as cyanide and cyanatescavengers.

Controlled- or sustained-release formulations of a pharmaceuticalcomposition of the invention may be made using conventional technology.

As used herein, “additional ingredients” include, but are not limitedto, one or more of the following: excipients; surface active agents;dispersing agents; inert diluents; granulating and disintegratingagents; binding agents; lubricating agents; sweetening agents; flavoringagents; coloring agents; preservatives; physiologically degradablecompositions such as gelatin; aqueous vehicles and solvents; oilyvehicles and solvents; suspending agents; dispersing or wetting agents;emulsifying agents, demulcents; buffers; salts; thickening agents;fillers; emulsifying agents; antioxidants; antibiotics; antifungalagents; stabilizing agents; and pharmaceutically acceptable polymeric orhydrophobic materials. Other “additional ingredients” which may beincluded in the pharmaceutical compositions of the invention are knownin the art and described, for example in Genaro, ed., 1985, Remington'sPharmaceutical Sciences, Mack Publishing Co., Easton, Pa., which isincorporated herein by reference.

Typically, dosages of the compound of the invention which may beadministered to an animal, such as a human, range in amount from 1 μg toabout 100 g per kilogram of body weight of the animal. While the precisedosage administered will vary depending upon any number of factors,including but not limited to, the type of animal and type of diseasestate being treated, the age of the animal and the route ofadministration. In one embodiment, the dosage of the compound will varyfrom about 1 mg to about 10 g per kilogram of body weight of the animal.In one embodiment, the dosage will vary from about 10 mg to about 1 gper kilogram of body weight of the animal.

The compound may be administered to an animal as frequently as severaltimes daily, or it may be administered less frequently, such as once aday, once a week, once every two weeks, once a month, or even leesfrequently, such as once every several months or even once a year orless. The frequency of the dose will be readily apparent to the skilledartisan and will depend upon any number of factors, such as, but notlimited to, the type of cancer being diagnosed, the type and severity ofthe condition or disease being treated, the type and age of the animal,etc.

Suitable preparations include injectables, either as liquid solutions orsuspensions, however, solid forms suitable for solution in, suspensionin, liquid prior to injection, may also be prepared. The preparation mayalso be emulsified, or the polypeptides encapsulated in liposomes. Theactive ingredients are often mixed with excipients which arepharmaceutically acceptable and compatible with the active ingredient.Suitable excipients are, for example, water saline, dextrose, glycerol,ethanol, or the like and combinations thereof. In addition, if desired,the vaccine preparation may also include minor amounts of auxiliarysubstances such as wetting or emulsifying agents, pH buffering agents,and/or adjuvants.

The invention also includes a kit comprising the composition of theinvention and an instructional material which describes adventitiallyadministering the composition to a cell or a tissue of a subject. Inanother embodiment, this kit comprises a (e.g., sterile) solventsuitable for dissolving or suspending the composition of the inventionprior to administering the compound to the subject.

As used herein, an “instructional material” includes a publication, arecording, a diagram, or any other medium of expression which can beused to communicate the usefulness of the peptide of the invention inthe kit for effecting alleviation of the various diseases or disordersrecited herein. Optionally, or alternately, the instructional materialmay describe one or more methods of using the compositions fordiagnostic or identification purposes or of alleviation the diseases ordisorders in a cell or a tissue of a mammal. The instructional materialof the kit of the invention may, for example, be affixed to a containerwhich contains the multimeric peptide of the invention or be shippedtogether with a container which contains the peptide. Alternatively, theinstructional material may be shipped separately from the container withthe intention that the instructional material and the compound be usedcooperatively by the recipient.

Other techniques known in the art may be used in the practice of thepresent invention.

The invention is now described with reference to the following Examplesand Embodiments. Without further description, it is believed that one ofordinary skill in the art can, using the preceding description and thefollowing illustrative examples, make and utilize the present inventionand practice the claimed methods. The following working examplestherefore, are provided for the purpose of illustration only andspecifically point out several embodiments of the present invention, andare not to be construed as limiting in any way the remainder of thedisclosure. Therefore, the examples should be construed to encompass anyand all variations which become evident as a result of the teachingprovided herein.

Additional therapeutic agents may also be administered, including, butnot limited to, anti-inflammatory agents, anti-microbial agents, etc.

The formulations of the pharmaceutical compositions described herein maybe prepared by any method known or hereafter developed in the art ofpharmacology. In general, such preparatory methods include the step ofbringing the active ingredient into association with a carrier or one ormore other accessory ingredients, and then, if desirable, shaping orpackaging the product into a desired single- or multi-dose unit.

The compounds of the invention may be administered to, for example, acell, a tissue, or a subject by any of several methods described hereinand by others which are known to those of skill in the art.

The relative amounts of the active ingredient, the pharmaceuticallyacceptable carrier, and any additional ingredients in a pharmaceuticalcomposition of the invention will vary, depending upon the identity,sex, age, size, and condition of the subject treated and furtherdepending upon the route by which the composition is to be administered.

In addition to the active ingredient, a composition of the invention mayfurther comprise one or more additional pharmaceutically active ortherapeutic agents. Particularly contemplated additional agents includeanti-emetics and scavengers such as cyanide and cyanate scavengers.

Controlled- or sustained-release formulations of a composition of theinvention may be made using conventional technology.

The source of active compound to be formulated will generally dependupon the particular form of the compound. Small organic molecules andpeptidyl or oligo fragments can be chemically synthesized and providedin a pure form suitable for pharmaceutical/cosmetic usage. Products ofnatural extracts can be purified according to techniques known in theart. Recombinant sources of compounds are also available to those ofordinary skill in the art.

Although the descriptions of pharmaceutical compositions provided hereinare principally directed to pharmaceutical compositions which aresuitable for ethical administration to humans, it will be understood bythe skilled artisan that such compositions are generally suitable foradministration to animals of all sorts.

The present invention encompasses biologically active analogs, homologs,derivatives, and modifications of the compounds of the invention.Methods for the preparation of such compounds are known in the art.

Liquid derivatives and natural extracts made directly from biologicalsources may be employed in the compositions of this invention in aconcentration (w/w) from about 1 to about 99%. Fractions of naturalextracts and protease inhibitors may have a different rage, from about0.01% to about 20% including from about 1% to about 10% of thecomposition. Of course, mixtures of the active agents of this inventionmay be combined and used together in the same formulation, or in serialapplications of different formulations.

EXAMPLES Example 1

Material and Methods

Summary

Human coronary ECs and SMCs were co-cultured and fractionated aspreviously described. iTRAQ proteomic screening was used to identify andquantify proteins enriched at the MEJ as previously demonstrated.Protein was analyzed using Western blot, immunofluorescence, and immunoTEM, while mRNA was measured using real-time-PCR. Isolated TD arterieswere cannulated, pressurized and stimulated with PE or Ach as previouslyshown or perfused with anaerobic aqueous nitric oxide.

Animals.

Wildtype C57Bl/6 male mice (Taconic) were 8-12 weeks of age. Mice werehoused and used in accordance with University of Virginia Animal Careand Use Committee guidelines.

Antibodies.

All antibodies source, application, concentration, and company purchasedfrom are listed in Table below

Blood Vessel Isolation.

Mice were sacrificed with CO₂ asphyxiation followed by thoracodorsal(TD) artery, mesenteric artery, epigastric abdominal feed artery,carotid artery and aorta isolation. As described in¹, isolated arterieswere placed into a Krebs-HEPES buffer supplemented with 1% BSA andwashed extensively abluminally and luminally using vessel cannulation toremove red blood cells. Arteries for immunolabeling were isolated frommice that were sacrificed with CO₂ and perfused transcardially with 5 mLof heparinized phosphate-buffered saline followed by 5 mL of 4%paraformaldehyde, or 0.5% glutaraldehyde/4% paraformaldehyde for immunotransmission electron microscopy (iTEM). Arteries were then isolated andfixed for an additional 30 minutes.

Vascular Cell Co-Culture (VCCC) Construction.

Human primary coronary endothelial cells (ECs) and smooth muscle cells(SMCs) (Lonza) were co-cultured as previously described^(2,3). Briefly,ECs were cultured in MCDB 131 (Gibco) supplemented with an EGM-2MVbullet kit (Lonza) plus 2 mM L-glutamine (Gibco). SMCs were cultured inDMEM/F12 (Gibco) supplemented with a SMGM-2 bullet kit (Lonza). Humanumbilical vein ECs (HUVEC) or SMCs (HUVSMCs) (Cell Applications Inc.)were grown in M199 media supplemented with 10% fetal bovine serum(Gibco), 2 mM L-glutamine (Gibco), and penicillin (2 mM)/streptomycin(50 U/mL) (Gibco). In addition, EC media was supplemented withendothelial growth supplement (5 μg/mL, BD Biosciences) and 5 μg/mL ofsodium heparin (Fisher Scientific). Following cell propagation, 9×10⁴SMCs were plated on a single Transwell (24 mm) for 24 hours, followed bythe addition of 3.6×10⁵ ECs plated on the opposite side of the sameTranswell. For 12 mm Transwells, 1.9×10⁴ SMCs and 9×10⁴ ECs were plated.Cells were co-cultured for an additional 72 hours.

VCCC Transfections.

VCCCs were constructed as described above. Following 24 hours postEC-SMC co culture, 2.5 μL of siPORT™ NeoFX™ (Ambion) and 100 nmol/L ofsiRNA or control non-targeting siRNA (ThermoFisher) (See Table below)were mixed in a 1 mL of Opti-MEM (Gibco). siRNA was added to EC only,SMC only or both for 48 hours. Samples were harvested for knockdownefficiency or used for NO assays.

In Vitro VCCC Fractionation.

In vitro EC, myoendothelial junction (MEJ) or SMC lysates were isolatedfrom VCCCs as previously described³.

cGMP Assay.

Isolated arteries or VCCCs were pretreated 30 minutes prior to PEstimulation with the phosphodiesterase inhibitor3-isobutyl-1-methylxanthine (IBMX-0.5 mM) and 100 μM L-Nitro-ArginineMethyl Ester L-NAME. Following PE stimulation (50 μM), samples wereisolated and lysed in buffer provided in the cGMP XP® Assay kit (CellSignaling) and the procedure was performed according to manufacturerinstructions. A standard curve of known cGMP concentrations was used todetermine the cGMP concentrations in the experimental samples. Resultswere then normalized to protein concentration.

Isobaric Tag for Relative and Quantitation Proteomics (iTRAQ).

The EC, MEJ, and SMC protein lysates were isolated as described above.Samples were frozen and shipped to the Yale Proteomics Facility (YaleUniversity, New Haven, Conn.) and detailed procedures were performed aspreviously described⁴. Briefly, 25 μg of each of the lysates werereduced and cysteines blocked as described in iTRAQ™ kit (AppliedBiosciences). Samples were trypsin digested overnight, followed bylabeling the N-terminus of lysine residues with iTRAQ labels 113, 115,and 117. Samples were pooled and purified using a strong cation exchangeand separated into 20 fractions. Samples were subjected to electrosprayionization using an Applied Biosystems API QSTAR XL mass spectrometer.Results generated were processed using Mascot Distiller and the databasewas searched using Mascot Server. Protein validation was then confirmedusing ProteinProphet. iTRAQ quantitation was performed using Paragon™search algorithm in ProteinProphet software. Proteins in the MEJfractions enriched compared to the EC or SMC lysates were consideredpositive.

Western Blot.

TD or carotid arteries, VCCC fractions or red blood cells were isolatedand homogenized in ice cold lysis buffer containing 50 mM Tris-HCL, 150mM NaCl, 5 mM EDTA, 1% deoxycholate, 1% NP-40 in phosphate bufferedsaline and pH adjusted to 7.4. Samples were sonicated and subjected toprotein electrophoresis using 4-12% Bis-Tris gels (Invitrogen) andtransferred to nitrocellulose. Blots were incubated with primaryantibodies (see Table below) overnight at 4° C. followed by washing.Protein was detected using Licor secondary antibodies (see Table below),visualized and quantitated using Licor Odyssey as previously described⁵.

Immuno TEM (ITEM).

Isolated TD arteries or carotid arteries were fixed as described above,embedded in LR White as previously described³ and labeled with primaryand secondary antibodies (see Table below). Images were taken on a Joel1220 electron microscope and gold bead quantitation was performed by aspreviously described³.

Immunostaining.

Immunostaining on paraffin sections from VCCC or isolated arteries wasperformed as previously described^(1,3). For en face staining, TD andcarotid arteries were cut longitudinally before the immunostainingprocedure. Antibodies used are in Table below. All images were acquiredusing a Fluoview 1000 confocal microscope (Olympus).

Realtime PCR.

Total RNA from arteries was extracted using Trizol (Invitrogen) whereastotal RNA from cells was extracted using an RNeasy Mini Kit spin column(Qiagen). RNA purity and concentration was quantified with a NanoDropspectrophotometer. cDNA synthesis (iScript cDNA Synthesis Kit—BioRad)and subsequent quantitative real-time reverse-transcription polymerasechain reaction (RT-PCR) analysis was performed using SYBR Green(BioRad), as previously described⁶. Gene-specific RT-PCR primers weredesigned using Primer3 (MIT) (see Table below) and correspondingproducts were sequenced for validation. Quantitative RT-PCR reactionswere run in duplicates and RNA abundance was normalized tobeta-2-microglobulin (B2M) or 18S ribosomal RNA.

Chemical Crosslinking.

Fractions from VCCCs, isolated TD arteries or red blood cells were lysedas described above and immediately placed on ice. Samples were douncedfor 1 minute using approximately 30 strokes and spun at 10 g at 4° C.Supernatants were removed and final concentration of 5 mM BS₃(ThermoFisher) was added to samples. After 30 minutes, 1 M Tris wasadded to each sample to quench the BS₃ followed by Western blot analysisfor quaternary structure determination.

Vasoreactivity.

TD arteries (maximal internal diameter 261.7±4.2 μm) were isolated,cannulated in a pressure myograph (Danish MyoTechnology) and securedwith 10.0 nylon sutures as described in⁷. The TD arteries were placed ina circulating bath of Krebs-HEPES and perfused with Krebs-HEPESsupplemented with 1% BSA. Arteries were maintained in a no flow stateand pressurized at 80 mmHg as previously described′. After 30 minutes ofequilibration, phenylephrine (PE, 50 μM) was added to the bath solutionand the contractile response was recorded for 15 minutes as describedin⁸. Acetylcholine (1 μM) was added to the bath to verify the integrityof the endothelium. Dose response curves were generated by addingcumulative concentrations of PE (1E⁻⁹-1E⁻²M). For Ach dose responses,vessels were preconstricted with 5-hydroxytryptamine (5-HT, 5×10⁻⁸ M)followed by cumulative concentrations of Ach (1E⁻¹⁰-3E⁻⁴ M). At the endof the experiments, the solution was replaced by a calcium-free Krebssupplemented with 2 mM ethylenbis-(oxyethylenenitrolo) tetra-acetic acid(EGTA) and 10 μM sodium nitroprussiate in order to measure the maximaldiameter. When indicated, propylthiouracil (PTU 50 μM) or the nitricoxide synthase inhibitor L-NAME (100 μM; Sigma) were added to the bathand intraluminally during the equilibration period. Internal diameterswere calculated and results are expressed as a percentage of initialinner diameter (for PE dose responses) or percent dilation (for Ach doseresponses). EC₅₀ and E_(max) values were calculated as previouslydescribed in⁹.

TD Artery Endothelium Transfection.

The TD arteries were isolated and cannulated as described above. Thevessel lumen was perfused with Krebs-HEPES buffer supplemented with 1%BSA to flush out red blood cells and 100 μL of Nucleofector transfectionreagent (HCAEC Nucleofector kit, Lonza) containing 10 nM control, Hb aor CytB5R3 siRNAs (see Table below) was perfused into the lumen.Arteries were then removed from the cannula and the ends ligated with10-0 nylon sutures to maintain the transfection reagent and siRNA in theblood vessel lumen. Ligated arteries were then transferred to atransfection cuvette (Lonza) containing 100 μL Nucleofector transfectionreagent and electroporated using the Nucleofector II Device (Lonza)using setting A-034. Transfected TDA were removed from cuvettes,re-cannulated and perfused with RPMI media+1% BSA to remove residualtransfection reagent and siRNA. Arteries were cultured for 15-18 hoursat 37° C. in RPMI+1% BSA and used for vasoreactivity studies orprocessed for immunofluorescence microscopy. To eliminate variability oftransfection efficiency and vessel viability, one control siRNA vesseland one Hb α/CytBSR3 vessel were transfected daily.

Generation of Anaerobic Nitric Oxide.

Anaerobic aqueous NO was generated by bubbling 100% helium into a beakercontaining deionized water. Following 30 minutes, 99.5% NO. gas wasbubbled for an additional 40 minutes giving a final saturatedconcentration of approximately 1.7 mM.

Nitric Oxide Diffusion Assay.

Both ECs and SMCs were cultured on 12 mm Transwells as described above.After three days of co-culture, media was removed and replaced with 500μL of Krebs buffer on each side of the Transwells and cells were allowedto equilibrate for 15 minutes. Next, 100 μL of anaerobic aqueous NO wasadded to the 500 μLs of Kreb's buffer on the EC side of the Transwell.After 5 minutes, 100 μL of Krebs buffer was immediately removed andinjected into a Seivers Nitric Oxide Analyzer (NOA). Data was quantifiedusing Origin Pro 6.0 by calculating the area under the peak over time.Differences between samples were expressed as μM change. For experimentson ex vivo samples, TD arteries were cannulated (as described above) inpuddle of 100 μL of Krebs buffer created by parafilm. Using two piecesof tubing, one piece connected to a manometer and an air tight 25 mLbottle and another tube connected to the air tight bottle and to a glasscannula where the TD artery is mounted, 300 μL of anaerobic NO was addedto 3 mL of Kreb's buffer into the air tight bottle. The bottle waspressurized to 80 mmHg allowing for a constant flow of through the lumenof the artery (flow rate was approximately 100 μL/minute). After 8minutes of flow through the vessel, Krebs's buffer on the abluminal sideof the vessel was injected into the NOA. Data was quantified usingOrigin Pro 6.0 by calculating the area under the peak over time.Differences between samples were expressed as μM change.

Nitric Oxide Consumption Assay.

The EC, MEJ, and SMC lysates or TD arteries and carotid arteries wereisolated as described above. Samples were assayed for NO consumption aspreviously described¹⁰. Briefly, a 40 mM stock solution of the NO donor(Z)-1-[2-(2-Aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate(DETA NONOate) in PBS was added to a glass vessel continuously purgedwith helium. This allowed for a continuous liberation of NO inducing asignal of approximately 50 mV due to decay DETA NONOate decay. Once thesignal stabilized, 100 μg of each sample was injected. Measurements ofdecreased NO signal were recorded and quantified using Origin Pro 6.0 bycalculating the area under the peak over time. NO gas standards wereused to generate a standard curve used determine the NO consumed in eachsample.

UV-Visible Spectrometry.

Isolated protein from VCCC fractions (500 μg) or TD arteries (500 μg)were placed in to a 96 well plate using a volume of 250 μL. Freshlyisolated human blood or methemoglobin (Sigma) were used as standards.Samples were read using a FLUOstar Omega star plate reader (BMG Labtech)by measuring the absorbance from 220-800 nm. Data was plotted in OriginPro 6.0 to generate curves and to compare samples.

Met-Hb α Reduction Assay.

Human coronary ECs were seeded in 100 mm dishes and grown toapproximately 80% confluency. ECs were then transfected with CytB5R3siRNA (see Table below) or CytB5R3-Flag tagged plasmid (5 μg, Origene)using Lipofectamine 2000 (Life Sciences) according to manufacturerdirections. After 24 hours, ECs were stimulated with the calciumionophore A23187 (1 μM) for 1 minute to maximize CytB5R3 activity. ECswere then lysed, protein concentrations were measured and transfectionefficiency was assessed via Western blot analysis as described above.Using a total of 300 μg of protein, EC lysates were mixed with purifiedHb α chains (25 μg/μl final concentration—isolated as described above),normalized to equal volumes with lysis buffer and placed immediately onice. Just before the spectral reading, 50 μM NADH (required for CytB5R3activity) was mixed with each sample and the full UV-visible spectrum(220-700) was measured at 0, 3 and 10 minutes. Changes in met-Hb αreduction was calculated by measuring the area between the 510-575 and610-650 nm peaks for the 0, 3, and 10 minute time points as shown inFIG. 4s (inset) using Origin Pro statistical software. Areas between510-575 and 610-650 nm were summed for each time point and the sum areaat time 0 minute was subtracted from the area at 3 and 10 minutes inorder to quantify the change in met-Hb α reduction.

Iron Oxidation State Assay.

Isolated protein from TD arteries (200 μg) or VCCC (100 μg) were dividedinto three tubes: one tube containing an untreated lysate, another with20 mM of ascorbic acid, and one with 0.6 mM potassium ferricyanide.Samples were incubated for 30 minutes at room temperature. After 30minutes, 10 mM of Ferene S, which only binds Fe²⁺, was added, andincubated for 1 hr at 37° C. followed by measuring absorbance of FereneS at 595 nm. A standard curve was generated using the ascorbic acid andpotassium ferricyanide values. Untreated samples were calculated usingthe standard curve and expressed as a % of Fe²⁺ and Fe³⁺. Thespecificity for hemoglobin was determined by knocking down Hb α withsiRNA.

Co-Immunoprecipitation.

Co-immunoprecipitations were performed as described in¹. Briefly,protein fractions were incubated with primary antibodies (see Tablebelow) overnight at 4° C. The following day, Dynabeads® were added tosamples for 2 hours at room temperature. Next, a magnet was used toisolate beads with the protein complexes. Laemmli sample buffer wasadded to beads and boiled for 1 minute. Beads were isolated and theproteins were subjected to Western blot analysis as described above.

For purified proteins, Hb α chains were isolated as previously describedwith modifications^(11,12). Lyophilized hemoglobin (Sigma) was broughtup to a final concentration of 50 mg/mL in 10 mM Tris, pH 8.0 at 4° C.Hemoglobin was passed through a DEAE Hi Trap column (GE Healthcare)using high pressure flow chromatograph at a flow rate of 1 mL/minute andHb α chains were collected as the flow through whereas β chains andtetramers remained bound to the column. Purified FLAG-tagged eNOS andCytB5R3 were purchased from Origene. For immunoprecipitationexperiments, 1 μg of each protein was mixed and incubated at 37° C. for1 hr. Following incubation, anti-FLAG magnetic beads (Sigma) were addedto the purified proteins for 1 hr and complexes were precipitated andanalyzed using Western blot as described above.

Proximity Ligation Assay (PLA).

Duolink® II fluorescence assay kit (Olink Bioscience) was used accordingto manufacturer instructions. Briefly, deparaffinized TD artery sectionswere incubated with primary antibodies (see Table below) overnight at 4°C. The next day, secondary antibodies conjugated with oligonucleotides(PLA probe PLUS and MINUS) were added to the sections and washed. Next,a ligation solution containing a ligase and two oligonucleotides wasadded to the tissue allowing for the PLA probe hybridization, only ifboth PLA probes were less than 30 nm apart. Lastly, an amplificationsolution consisting of nucleotides and fluorescently labeledoligonucleotides was added along with a polymerase. Rolling-circleamplification was then initiated and fluorescently labeledoligonucleotides were hybridized to the amplification product. Arterieswere then imaged using an Olympus Fluoview 1000 confocal microscope.

NO_(x) Measurements.

Total NO metabolites (NOx) were assayed as described⁸. Briefly, sampleswere injected in a purged glass vessel heated to 95° C. containing asolution of vanadium (III) chloride (50 mM) in hydrochloric acid (1 mM),with a continuous purged stream of helium. NO signal was measured bychemiluminescence using a NO analyzer.

Measurement of S-nitrosylated N-acetyl Cysteine (SNO-NAC).

Experimental setup was performed similarly as describe above in Nitricoxide diffusion assay. Isolated arteries were cannulated and placed intoa puddle of 150 μl NAC (1 μM) on the ablumenal side, which served as aS-nitrosothiol bait reactant¹³. Next, using a manometer connected to apressurized bottle (described above), a solution of DETA NONOate (100μM) was passed through the lumen of the vessel for 1 hr. The puddle ofNAC was then subjected to the copper/cysteine assay to measure SNO-NACdescribed in¹⁴. For VCCCs, 1 μM NAC in KREBs was placed on the SMCs ofthe VCCC and a solution of DETA NONOate (100 04) in Krebs was then addedto the EC side of Transwell. After 1 hr, the buffer was measured fortotal SNO-NAC by the copper/cysteine assay.

Modeling of Hb α, CytB5R3, and eNOS.

The crystal structures of Hb α (1Y01) and eNOS (3NOS) had small regionsof the proteins not built into the crystal structure model.SWISS-MODEL^(15,16) was used to build in the missing regions using theoriginal structure as the template. The GRAMM-X server^(17,18,19) wasused to generate 20 poses of Hb α and CytB5R3 (1UMK). Of the 20 poses,two poses were removed as possibilities because the dimer interface hadthe least buried surface area. The remaining 18 poses were evaluatedbased on the accessibility of three CytB5R3 residues (K41, K125, andK162) identified as essential for binding to CytB5²⁰. The remaining 18poses were analyzed based on frequency of the interaction with face ofHb α and the sampling of orientations with respect to the face of Hb α.Nine poses remained which clustered into six groups based on theinteraction face of Hb α; three groups with a single pose (which werenot used for further analysis) and three groups each with two poses(clusters). The poses in one of the three clusters had very differentCytB5R3 interactions with Hb α and; therefore, were not furtheranalyzed. In the remaining two clusters, two pose were very similar inthe orientation of CytB5R3 with respect to the face of Hb α and twoposes interacted with the same surface of Hb α, but the orientation ofCytB5R3 were 180° rotated with respect to each other. A representativeHb α/CytB5R3 homodimer from each of these two clusters was docked to theeNOS dimer. Of the 40 poses (20 poses for each Hb α/CytB5R3 docked), 27docked to an interface between the two eNOS monomers. The poses had manyorientations at the interface; however, there was a significant bias tothe interface. To generate the final model, the symmetry mate wasgenerated such that the other docking site of eNOS was occupied and thestoichiometry was 1:1:1. The low-resolution model shown is only one ofthe poses and is shown in surface representation so that the exactinterfaces are not over-interpreted.

Statistics.

Statistics were performed using Origin Pro 6.0 software. For multiplecomparisons, statistics were performed using a one-way by pairwiseanalysis. A Student's t-test was used for individual comparisons ifnormally distributed. For vascular reactivity cumulative concentrationresponse curves, a two ANOVA was performed followed by a Bonferronipost-hoc test using GraphPad Prism 5.

Table 3

TABLE 3 Table 3 - Catalog of Antibodies. Antibody Species ApplicationCouc. Company Cat. Number Hb α rabbit WB, IF, IP, 1:1000, 1:500, 1:50Abcam ab102758 ITEM 1:50 Hb α goat PLA 1:500, 1:100 Santa Cruz sc-31109Hb β goat WB 1:1000 Santa Cruz sc-31116 Hb β mouse WB 1:1000 Santa Cruzsc-21757 AHSP rat IF 1:500 Gift from Mitchell N/A Weiss AHSP rabbit WB1:1000 Gift from Mitchell N/A Weiss Cytoglobin rabbit WB 1:1000Proteintech 13317-1-AP CyB5R3 rabbit WB, IF, IP, 1:1000, 1:500, 1:50Proteintech 10894-1-AP PLA, iTEM 1:100, 1:50 eNOS mouse WB, IF 1:1000,1:500 BD Biosciences 610296 eNOS rabbit PLA 1:100 Sigma N 3893 tubulinrabbit WB 1:10,000 Sigma T 2200 GAPDH mouse WB 1:10,000 Invitrogen39-8600 Alexa488 mouse IF 1:500 Invitrogen A-21442 Alexa594 rabbit IF1:500 Invitrogen A-21202 Licor 700 mouse WB 1:5000 Licor 926-32220 Licor800 rabbit WB 1:5000 Licor 926-32211 Gold beads rabbit iTEM 1:50Electron Microscopy 25109 (10 nm) Services Lists are the antibodiesused, the species the antibody was produced in, application for theantibody, the concentration of antibody used for each applicationrespectively, the company where the antibody was produced and thecatalog number. WB—Western blot, IP-immunoflourescence,IP—immunoprecipitation, iTEM—immuno transmission microscopy,PLA—proximity ligation assay.Table 4

TABLE 4 Gene (Accession Primer Sequence Product number) (5′-3′)Size (bp) h-Hb α (F)TGGACCCGGTCAACTTCAA 160 (NM_000558.3)(R)GAGGCTCCAGCTTAACGGTA T m-Hb α (F)TGCTCTCTGGGGAAGACAAA 154(NM_001218.2) (R)GAGCCCTGCCTTACATCAA h, m-Cytoglobin(F)tcggccaagcagtacttcag 239 (NM_134268.4, (R)ACCTCCAGAATGACCCCAGANM_030206.4) b-Neuroglobin (F)TCCTGGACCACATCAGGAAG 151 (NM_021257.3)(R)TCACCCACTGTCGAGAAGGA m-Neuroglobin (F)TCCTGGACCACATCAGGAAG 182(NM_022414.2) (R)CAGGCACTTCTCCAGCATGT h-Myoglobin(F)GGCTCTTTAAGGGTCACCCA 174 (NM_005368.2) (R)GGGGCTTAATCTCTGCCTCAm-Myoglobin (F)CTGAATGTCTGGGGGAAGGT 243 (NM_ (R)TTGGGCTAGAGGCTGGATCT001164047.1) The left side lists the gene name and accession number inwhich primers were designed. The middle column shows the forward andreverse 5′-3′ primer sequences. The right column indicates theapproximate base pair size of each product. h-human, m-mouse.Table 5

TABLE 5 siRNA ID Anti-sense  siRNA (Ambion) Sense (5′-3′) (5′-3′)Application Conc. m-Hb-α S67374 GCAUGCCUCUC UUUGUCCAGAG vessel  10 nMUGGACAAATT AGGGAUGCAC transfection (SEQ NO: 24) (SEQ NO: 25) m-Hb-αS67376 GACCUACUUCC AAAGUGAGGGA vessel  10 nM CUCACUUUTT AGUAGGUCTTtransfection (SEQ NO: 26) (SEQ NO: 27) h-Hb-α S194496 CAAAUACCGUUUCCAGCUUAAC VCCC 100 nM AAGCUGGATT GGUAUUUGGA transfection (SEQ NO: 28)(SEQ NO: 29) h-Hb-α S194498 ACUUCAAGCUC UGGCUUAGGAG VCCC 100 nMCUAAGCCATT CUUGAAGUTG transfection (SEQ NO: 30) (SEQ NO: 31) m-CytB5R3S99607 AGGGCUUCGUG UCCUCAUUCAC vessel  10 nM AAUGAGGATT GAAGCCCUCCtransfection (SEQ NO: 32) (SEQ NO: 33) m-CytB5R3 S99606 GGACACCCAUCAAACUUGGGAU vessel  10 nM CCAAGUUUTT GGGUGUCCTT transfection(SEQ NO: 34) (SEQ NO: 35) h-CytB5R3 S4087 GGAGGAACUCA UUUGUUCCUGA VCCC100 nM GGAACAAATT GUUCCUCCAG transfection (SEQ NO: 36) (SEQ NO: 37)h-CytB5R3 S4088 GACAAAAAGUC UAGGGUUGGAC VCCC 100 nM CAACCCUATTUUUUUGUCAG transfection (SEQ NO: 38) (SEQ NO: 39) List of siRNAsequences. The siRNA shows the gene target of interest, the siRNA IDindicates the catalog identification code from Ambion, the targetingsequence shows the sense (5-3′) and antisense (3′-5′), the applicationlists the experiment in which the siRNA was used and the concentrationshows how much siRNA was used for each application. h-human, m-mouse.

PE stimulation of thoracodorsal (TD) arteries ex vivo—and of primaryhuman ECs and vascular smooth muscle cells (SMCs) in the vascular cellco-culture (VCCC) model—reproduced classical NOS- and cGMP-dependentchanges in SMC biology (FIG. 5a-d ). However, NO did not diffuse intothe extracellular space (FIG. 5e-h ), consistent with previous workshowing compartmentalized NOS signaling at the MEJ, the EC-SMC contactpoint in the TD and other small arteries and arterioles. Therefore, MEJproteins that could contribute to local regulation of NO diffusion andbiochemistry were studied. A proteomic analysis of MEJs isolated fromVCCCs using the isobaric tags for relative and absolute quantitation(iTRAQ) system was performed (FIG. 6). Surprisingly, Hb α was abundantat the MEJ (FIG. 7). Without wishing to be bound by any particular, itwas hypothesized that Hb can regulate NO diffusion and biochemistry atthe MEJ and the experiments and results directed to that hypothesis areprovide below.

First, the proteomic data using immunoblot and immunofluorescence wasconfirmed. Hb α protein expression in the VCCC model, but no expressionof Hb 13 was demonstrated (FIG. 1a ). There was little Hb α expressionin human ECs or SMCs grown separately, and there was no Hb α in thefibronectin or gelatin used to coat the VCCC transwells (FIG. 1a ).Next, these results were confirmed in co-cultures of different types ofECs and SMCs where MEJs also expressed abundant Hb α (FIG. 8). The MEJdistribution of Hb α in situ was then examined. Gold particles labelingHb α were abundant in the MEJ of mouse TD arteries visualized bytransmission electron microscopy (TEM) (FIG. 1b ). In contrast, carotidarteries—conduit arteries which have few MEJs—expressed little Hb α asobserved by TEM (FIG. 1b ), immunoblot (FIG. 1c ), andimmunofluorescence (FIG. 1d ). These data were consistent in humanskeletal muscle arterioles (FIG. 1d ) and throughout multiple tissuebeds (FIG. 9). Using en face immunofluorescence, punctuate Hb α stainingprimarily at paracellular junctions of TD—but not carotid—arteries wasfound, whereas little Hb β was observed (FIG. 1e ). Chemicalcrosslinking analysis revealed that the Hb α was monomeric in TDarteries and the VCCC (FIG. 1f ). Next, Hb α mRNA was measured usingreal-time PCR (FIG. 1g ) and established that ECs transfected with Hb αsiRNA had decreased protein expression at the MEJ (FIG. 20a ) and in themonolayer (FIG. 10b ). Loss of Hb α protein expression did not affecteNOS expression in the EC monolayer (FIG. 10b ) or at the MEJ (FIG. 11).

Transcripts for other globins including myoglobin, neuroglobin, andcytoglobin were absent in ECs (FIG. 12a-c ). Only cytoglobin mRNA andprotein were expressed in SMCs (FIG. 12c-d ), consistent with a previousreport. In addition, Hb α stabilizing protein in the endothelium of TDarteries and in the VCCC was found (FIG. 13a-b ). Taken together, thesedata show for the first time that arterial ECs express Hb α mRNA andprotein and are responsible for enriched Hb α expression at the MEJ.

To investigate the functional role of Hb α in ECs and its effect on eNOSsignaling, ECs in isolated TD arteries were transfected with Hb α orcontrol siRNA. Knockdown efficiency was 70-80% (FIG. 14). Loss of Hb αresulted in a dramatic loss in arterial reactivity following PEapplication in a single or cumulative doses (FIG. 2a-b ) and increasedreactivity to acetylcholine (Ach) (FIG. 2c ), but there was no change inresponse to 5-hydroxytryptamine (5-HT) (Table 1). EC₅₀ and E_(max)values are in Table 2. No difference was observed in basal tone (FIG.15a ). However, with the addition of the NOS inhibitorL-N^(G)-nitroarginine methyl ester (L-NAME), the effect of Hb α siRNAwas comparable to control conditions for both PE and Ach responses (FIG.2a-c ). It was thus hypothesized that eNOS, the primary isoform in thevessel wall, may be in close spatial proximity to Hb α. This wasinvestigated using four methods: co-localization studies byimmunofluorescence (FIG. 2d,g ), a proximity ligation assay (FIG. 2e ),and co-immunoprecipitations from cell lysates (FIG. 2f,h ) and purifiedproteins (FIG. 2i ). These analyses revealed Hb α and eNOS are in amacromolecular complex and can form a direct protein-proteininteraction.

Table 1

TABLE 1 Table 1 - The effect of 5-HT induced contraction on TD arterieswith HB α or CYT5BR3 knockdown or PTU pretreatment in the presence orabsence of L-NAME. Contraction to 5-HT 50 nM Post 15 min % initialdiameter Control sirNa 52.41 ± 7.4 Control sirNa + L-NAME 48.11 ± 4.69n.s. Hb α siRNA 62.19 ± 1.82 n.s. CytB5R3 siRNA  63.2 ± 3.7 n.s. Control 63.3 ± 6.2 Control + L-NAME  57.0 ± 3.29 n.s. PTU  64.1 ± 4.5 n.s.Vessels transfected with HB α or CytB5R3 siRNA or pretreated with PTU(50 μM) in the presence or absence of L-NAME were stimulated with 5-HT(50 nm). The % initial diameter was quantified 15 minutes afterstimulation (n = 3). n.s. indicates not significant.Table 2

TABLE 2 Table 2 - Pharmacological properties for PE and Ach cumulativeconcentration response curves (CCRC) after siRNA knockdown with Hb α orCytB5R3 or pretreatment with PTU. PE CCRC EC₅₀ and E_(max) EC₅₀ (μM)E_(max) (% initial diameter) Control siRNA 2.577 ± 0.508 19.0 ± 2.9 HbasiRNA 0.196 ± 0.084*  71.8 ± 4.2* CyB5R3 siRNA 0.416 ± 0.172*  68.1 ±4.0* Control siRNA + L-NAME 0.426 ± 0.038 23.1 ± 2.8 Hba siRNA + L-NAME1.885 ± 0.397{circumflex over ( )} 22.4 ± 1.9{circumflex over ( )}CytB5R3 SiRNA + L-NAME 0.531 ± 0.085 26.8 ± 4.0{circumflex over ( )} AchCCRC EC₅₀ and E_(max) EC₅₀ (μM) E_(max) (% Dilation) Control siRNA2.7274 ± 0.496  88.6 ± 5.0 Hba siRNA  0.077 ± 0.010* 86.8 ± 4.2 CyB5R3siRNA  0.355 ± 0.235*  93.9 ± 10.6 Control siRNA + L-NAME 1.185 ± 0.38980.7 ± 6.3 Hba siRNA + L-NAME 0.882 ± 0.305 76.7 ± 2.7 CytB5R3 SiRNA +L-NAME 1.469 ± 0.282 83.7 ± 1.6 PE CCRC EC₅₀ and E_(max) EC₅₀ (μM)E_(max) (% initial diameter) Control 1.206 ± 0.357 60.6 ± 1.9 PTU 6.623± 4.697 91.4 ± 2.5# L-NAME 1.534 ± 0.357 62.6 ± 6.1 PTU + L-NAME 0.454 ±0.148 60.4 ± 7.8♦ Ach CCRC EC₅₀ and E_(max) EC₅₀ (μM) E_(max) (%Dilation) Control 33.7 ± 6.4 97.4 ± 2.5 PTU 21.9 ± 7.7 94.9 ± 1.7 Theleft column represents each condition, the middle column shows the 50%of maximal effective concentration ((EC₅₀)-in μM) for both PE and Achand the right column indicates the maximum effective concentration(E_(max)) expressed as the % of initial diameter for PE and % dilutionfor Ach. *indicates significance between control siRNA vs. Hb α/CytB5R3siRNA and {circumflex over ( )} shows significance between control siRNAvs. Hb α + L-NAME/CytB5R3 + L-AME siRNA for both EC₅₀ and E_(max).#indicates significance between control vs. PTU and black diamond showssignificance between PTU vs. PTU + L-NAME.

Without wishing to be bound by any particular theory, it is hypothesizedherein that Hb α likely interacts with eNOS to regulate blood vesseltone by controlling NO diffusion through its scavenging by heme iron.The mechanism of interaction by measuring loss of NO radical in TD andcarotid arteries, and in the VCCC model was studied. NO was lost in TDarteries, but not carotid arteries; and it was lost in MEJ fractions—butnot EC or SMC—lysates (FIG. 16a-b ). Next, endothelial Hb α in isolatedarteries (FIG. 2j ) or VCCCs (FIG. 2l ) was knocked down using siRNA.Loss of Hb α increased NO diffusion across the vessel wall (FIG. 2k )and in the VCCC (FIG. 2m ). Together, these results indicate thatendothelial Hb α can regulate arterial tone through its effects on NOdiffusion.

Next, it was hypothesized that Hb α heme iron in the oxygenated Fe²⁺state should control NO diffusion through a fast reaction (2.4×10⁷M⁻¹·sec-1) resulting in dioxygenation, whereas Fe³⁺ state should permitNO diffusion due to a slower reaction rate (3.3×10³M-1·sec⁻¹). It wasfound that Hb α heme iron resides in both states. First, usingUV-visible spectroscopy, a Soret peak (˜420 nm) and Q bands (˜540-575nm) in isolated TD arteries was identified consistent with oxygen boundHb Fe²⁺, whereas there was no peak in carotid arteries (FIG. 3a ). Next,the oxidation state of Fe was measured and found approximately 42%existed in the Fe²⁺ and 58% in the Fe³⁺ state (FIG. 3b ). Thesemeasurements were sensitive to Hb α siRNA (FIG. 3b ). Consistent withthis observation, it was found that carbon monoxide (CO) ligated Fe²⁺heme, resulted in increased NO diffusion across isolated vessels (FIG.16c ). When MEJ fractions were studied, a Soret peak (˜410 nm)characteristic of the Fe³⁺ state (methemoglobin) was found (FIG. 3c ).Interestingly, pelleted membranes from MEJ fractions were dark brown,consistent with Fe³⁺ oxidation (FIG. 17). It was also foundapproximately 32% of Fe existed in the Fe²⁺ and 68% in the Fe³⁺ state(FIG. 3d ), results that were also sensitive to Hb α siRNA (FIG. 3d ).An increase in NO diffusion in VCCCs treated with CO was also observed(FIG. 16d ).

Previous work has demonstrated that NO-heme Fe³⁺ interaction results inreductive nitrosylation, a mechanism known to generate S-nitrosothiols,which has been shown to have a role in gap junction regulation at theMEJ. Using N-acetylcysteine as a bait reactant on the abluminal side(FIG. 18a,c ), a striking loss of S-nitrosothiol synthesis after Hb αknock down in TD arteries (FIG. 18b ) and in the VCCC was found (FIG.18d ). Together, these results suggest that Hb α heme oxidation stateregulates both NO diffusion and bioactivation.

Next the mechanism regulating Hb α oxidation state was investigated. Inerythrocytes, cytochrome B5 reductase 3 (CytB5R3) or diaphorase 1, aknown methemoglobin reductase, controls the heme iron oxidation statethrough reduction of Fe³⁺⁶. Using immunofluorescence (in vivo FIG. 4a ,in vitro FIG. 4e ), TEM (FIG. 4b ), and Western blot analysis (in vivoFIG. 4c , in vitro 4 d), it was identified that CytB5R3 was expressed inECs and at the MEJ. In addition, it was established that CytB5R3 is in acomplex with Hb α using four separate assays: immunofluorescence (FIG.4f-g ), proximity ligation assay (FIG. 4h ), and co-immunoprecipitationfrom cell lysates and purified proteins (FIG. 4i ). Indeed, molecularmodeling of the crystal structures for Hb α, eNOS, and CytB5R3 revealeda discreet region of high probability where the proteins could interact(FIG. 19). Next, CytB5R3 siRNA (knockdown efficiency: ˜50%, FIG. 20a )and overexpression was used to show that CytB5R3 regulates metHb αreduction. Time lapse UV-visible spectrometry demonstrated that loss ofCytB5R3 inhibited metHb α reduction and that overexpression enhancedmetHb α reduction (FIG. 20b-c ). To determine if CytB5R3 expression oractivity regulates arterial tone, both siRNA directed againstendothelial CytB5R3 in TD arteries and a pharmacological inhibitor ofCytB5R3, propylthiouracil (PTU) were tested. Knockdown efficiency wasabout 70% (FIG. 21a ). A decrease in arterial reactivity in TD arteriestransfected with CytB5R3 siRNA after PE stimulation with a single doseor cumulative concentrations (FIG. 4j-k ) and increased reactivity withACh dose response was observed (FIG. 4l ). Vascular reactivity to PE orAch in TD arteries pretreated with PTU is shown in (FIG. 22a-c ). Theeffect with PTU was not reversible with L-thyroxine supplementationafter PE stimulation (FIG. 22b , inset). However, no change was foundwith 5-HT (Table 1). EC₅₀ and E_(max) values are in Table 2. However,with the addition of L-NAME, the effect of CytB5R3 siRNA was comparableto control conditions (FIG. 4j-l ) or PTU treated arteries (FIG. 22a-b), results that were consistent with Hb α knockdown. No difference inbasal tone for CytB5R3 siRNA or PTU was found (FIG. 15a-b ). Next theeffect of CytB5R3 on NO diffusion in vessels and VCCC was investigated(FIG. 4m,o ). Knockdown of CytB5R3 siRNA was ˜30% at the MEJ (FIG. 21b )and in the EC monolayer but not in SMCs (FIG. 21c ). Both CytB5R3 siRNAand PTU treatment increased NO diffusion across both isolated vesselsand in VCCC (FIG. 4n, p ; FIG. 22d-g ). Note that CytB5R3 knockdown didnot alter MEJ eNOS or Hb α expression (FIG. 21d ).

It is concluded that EC expression of Hb α plays a role in theregulation of NOS-mediated signaling and in the control of arterialvascular reactivity. These results have far reaching implications thatcan influence many aspects of vascular biology and disease. For example,endothelial Hb α expression may participate in blood pressure control,arteriogenesis and anti-inflammatory signaling, as well as impact otherredox signaling molecules (e.g. superoxide and hydrogen peroxide). Thepresent invention therefore encompasses methods for regulating theseprocesses using the compositions and method of the invention. Indeed,the results disclosed herein correlate with diagnostic indices for humanalpha thalassemia major (Hb α^(−/− −/−)) fetuses, who show increasedcerebral blood flow during development. Furthermore, these observationscan explain why inhibition of CytB5R3 attenuates hypertension. Takentogether, these data provide evidence for a novel paradigm in whichsomatic cell Hb oxidation is required for NO-dependent bioactivity.

BIBLIOGRAPHY

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Example 2

Introduction

Peripheral vascular resistance, a component of blood pressureregulation, is governed by arterial blood vessel tone. The regulation ofvascular tone involves a complex set of cell-cell signaling mechanismsbetween endothelium and vascular smooth muscle, and it is documentedthat molecules released from the endothelium (e.g. nitric oxide (NO),endothelium derived hyperpolarizing factor, prostaglandins) influencethis process¹⁻⁶. For example, signals originating from vascular smoothmuscle stimulate the release of endothelium-derived NO to modulate thecontractile response during α1D-adrenergic-mediatedvasoconstriction^(7,8). Thus, a balance between contractile and dilatorysignaling events is maintained during vasoconstriction.

Recent work has demonstrated that endothelial cell expressed hemoglobinα (Hb α) at the myoendothelial junction (MEJ) is a key regulator of NOdiffusion to vascular smooth muscle during vasoconstriction in isolatedthoracodorsal arteries⁹. It was discovered that the Hb α heme ironoxidation state, controlled via cytochrome B5 reductase 3, operates as aswitch to either permit NO diffusion or NO scavenging 9. From thesestudies, the role of Hb α at the MEJ both in small arteries and in avascular cell co-culture (VCCC) was elucidated. Of particular interest,it was observed that Hb α and eNOS form a macromolecular protein complexat the myoendothelial junction and can bind directly to each other shownin small arteries, the VCCC or purified proteins⁹. These data provide apotential mechanism by which Hb α/eNOS protein-protein interaction canregulate NO signaling during vasoconstriction. Thus, it is believed thateNOS/Hb α coupling may play a role in NO signaling and a novel Hb apeptide mimetic was created to investigate this interaction onfunctional outputs such as vasoconstriction and blood pressure.

Materials and Methods

In Silico Modeling and Peptide Generation:

Modeling interactions of crystal structures between Hb α (PDB number1Y01) and the oxygenase domain of eNOS (PDB number 3NOS) were performedusing a GRAMMX server as previously described⁹. Visualization ofmolecular interactions and predicted sequence identification wasperformed using PyMOL software. To accomplish this, interface regions ofHb α with eNOS were identified by selectively removing non-interactingregions, which resulted in the identification of a specific Hb α peptidesequence. The identified sequence was blasted against other mammalianspecies to determine peptide conservation. Peptides analogous to thefirst ten amino acids of Hb α (LSFPTTKTYF; SEQ ID NO:2) or a scrambledpeptide (FPYFSTKLTT; SEQ ID NO:40) were generated with the addition ofan HIV-tat tag (YGRKKRRQRRR; SEQ ID NO:3) to the N-terminus for plasmamembrane permeability required in subsequent studies. Peptides werenamed Hb α X and Scr X respectively. For internalization studies, afluorescein isothiocyanate (FITC) tagged Hb α X peptide was generated.All peptides were synthesized and purchased from AnaSpec. Purified eNOSand Hb α Protein Interaction Studies:

Purified Flag-eNOS was purchased from Origene and isolated Hb α chainswere generated as previously described⁹. Co-immunoprecipitation studieswere performed by incubating 1 μg of Flag-eNOS with 5 μmol/L of eachpeptide (tat-only, Scr X or Hb α X) for 30 minutes at 37° C. whileshaking. Then, 1 μg of isolated Hb α chains were added to theFlag-eNOS/peptide complex for an additional 30 minutes at 37° C.shaking. Anti-Flag nickel beads, blocked with 1% bovine albumin serumfor 1 hour, were added to each condition for an additional hour withagitation. Proteins were washed 3x with PBS for 15 minutes and purifiedprotein-protein complexes were precipitated using a strong magnet. Thenickel beads were incubated with 5×SDS PAGE buffer to elute proteins offthe beads. Samples were subjected to Western blot analysis to determinepeptide-induced disruption of Hb α and eNOS binding.

Mice:

Male C57BL/6 mice or eNOS^(−/−) between the ages of 10-12 weeks werepurchased from Taconic Farms or Jackson Labs and were used according tothe University of Virginia Animal Care and Use Committee guidelines.

Coronary Endothelial Cell Culture and Stimulation:

Primary coronary endothelial cells (Lonza) were cultured on plastic6-well dishes as previously described⁹. For studies involving basal NOrelease, endothelial cells were incubated with 5 μmol/L of Scr X or Hb αX for 20 minutes followed by medium collection and nitrite measurementsas described below. For bradykinin studies, coronary endothelial cellswere grown to confluence followed by serum starvation overnight in acocktail of Lonza EGM-2 medium supplemented with EGM-2 bullet kit andOpti MEM reduced growth medium using a ratio of 1:9 respectively. Thenext day, endothelial cells were incubated with Scr X or Hb α X peptidefor 20 minutes followed by the addition of 10 μM bradykinin (Sigma) for5 minutes followed by medium collection for nitrite measurements asdescribed below.

Visualization of HbX-FITC Peptide and Hbα in the Holes of the InternalElastic Lamina:

Thoracodorsal arteries were isolated from C57BL/6 mice and immediatelyplaced in Krebs-HEPES buffer. Each artery was cannulated in the chamberof a pressure myograph (Danish Myo Technology) filled with Krebs-HEPESand the lumen was perfused and pressurized at 80 mmHg with Krebs-HEPEScontaining 1% BSA. After a 30 minute equilibration period, the lumen wasperfused with the HbX peptide-FITC (5 μmol/L) for 20 minutes. The lumenwas then washed with calcium-free Krebs-HEPES and fixed with PFA 4% for30 minutes. After washing with Krebs-HEPES, the lumen was perfused for30 minutes with blocking solution (5% goat serum, 0.5% BSA, and 0.25%Triton X in PBS) while the pressure myograph chamber was filled with thesame blocking solution. The primary antibody (rabbit anti-Hbα, Abcam,1/100 in blocking solution) was perfused through the lumen for 10minutes and the TD arteries were removed from the cannula and placed inan individual well of a 96 well-plate filled with blocking solution andthe primary antibody and incubated overnight at 4° C. Next the TDarteries were cannulated again to wash out excess primary antibody.After the washes, Rhodamine Red-conjugated goat anti-rabbit (JacksonImmunoResearch, 1/50 in blocking solution) was perfused luminally andabluminally. The TD artery was placed in a well of a 96 well-platecontaining the secondary antibody in blocking solution for 30 minutes atroom temperature. The TD arteries were cannulated again in the pressuremyograph to wash out excess secondary antibody luminally and abluminallywith calcium-free Krebs-HEPES. Lastly, the lumen was perfused withAlexaFluor633-conjugated sodium hydrazide (Molecular Probes, 0.2 μM incalcium-free Krebs-HEPES) to mark elastin for 20 minutes and the excessdye was further washed for 10 minutes. This technique was based uponpreviously published methods for protein visualization within the holesof the IEL^(10,11). At the end of the experiment, the TD artery wasremoved from the cannula at one end while the other end was stillsecured and the vessel still pressurized. The TD artery was then cutlongitudinally from the unattached end and placed on a glass slide withthe luminal side facing down and the excess saline solution removed. Asingle drop of DAPI mounting medium (ProLong Gold, Invitrogen) wasplaced next to the vessel and a coverslip was positioned on the vessel.The mounting medium was allowed to diffuse between the slide and thecoverslip for 10 minutes while a weight was placed on the coverslip toensure flattening of the artery for microscopy. The coverslip was sealedwith nail polish and viewed on an Olympus FV1000 confocal microscope.For quantification purposes, the peptide and Hb α were each determinedto be present in the holes of the IEL if fluorescence was >50% maximalintensity, and only within or on the physical boundaries of the hole asdetermined by the AlexaFluor633 sodium hydrazide.

Proximity Ligation Assay and Quantitation on Thoracodorsal Arteries:

Isolated thoracodorsal arteries were perfused with Scr X or Hb α Xpeptide (5 μmol/L) for 20 minutes and immediately immersed in 4%paraformaldehyde, paraffin-embedded and sectioned as previouslydescribed¹². Next, sections were de-paraffinized, blocked and incubatedwith 1:500 mouse anti-eNOS (BD Biosciences), 1:500 rabbit anti-Hb α and1:500 mouse anti-caveolin-1 (BD Biosciences) primary antibodiesovernight at 4° C. The following day, secondary antibodies conjugatedwith oligonucleotide PLA probes were added, ligated and rolling circleamplification with fluorescent oligonucleotides identified positiveinteraction sites as previously described⁹. All images were visualizedand captured using an Olympus Fluoview 1000 confocal microscope. Forproximity ligation assay quantitation, positive interactions indicatedby red punctates on the endothelium were counted and divided by thecircumference of the lumen using Metamorph software.

Western Blot Analysis of Coronary Endothelial Cell Lysates:

Endothelial cells were harvested in lysis buffer, sonicated andsubjected to electrophoresis using 10% Bis-Tris gels (Invitrogen) aspreviously described¹³. Proteins were transferred to nitrocellulose,incubated with phospho-eNOS 51177 (BD Biosciences) or total eNOS (Sigma)and visualized and quantitated using Li-Cor Odyssey Imager as previouslydescribed¹⁴.

Nitrite Measurements from Media of Coronary Endothelial Cells:

Quantitation of nitrite in culture medium was measured bychemiluminescence using a Sievers nitric oxide analyzer according tomanufacturer's instructions. Quantitation of peaks was analyzed usingOrigin Pro 6.0 as previously described⁹.

cGMP Assay on Thoracodorsal Arteries:

Isolated thoracodorsal arteries were cannulated and pressurized to 80mmHg as previously described¹³. Arteries were perfused with 5 μM Scr Xor Hb α X with addition of 0.5 mmol/L of the phosphodiesterase inhibitor3-isobutyl- 1-methylxanthine (IBMX) (all conditions) or 100 μmol/L thenitric oxide synthase inhibitor L-NG-Nitroarginine Methyl Ester (L-NAME)for 20 minutes. Arteries were then stimulated with 50 μM phenylephrinefor 10 minutes and immediately immersed in lysis buffer provided in thecGMP XP assay Kit (Cell Signaling) according to manufacturesinstructions. Briefly, a competition enzyme-linked immunoassay was usedto generate a standard curve of known cGMP concentrations followed bycalculating cGMP concentrations of experimental samples. The cGMPconcentration in experimental samples was normalized to total proteinconcentration.

Pressure Myography on Thoracodorsal Arteries:

Thoracodorsal arteries were isolated, cannulated and pressurized in aDanish Myo Technology (DMT) pressure myograph as previously described¹³.Following 10 minutes of equilibration, vessels were perfused luminallywith Scr X or Hb α X peptide and incubated for an additional 20 minutes.Contractile responses were studied using cumulative concentrations(10⁻⁹-10⁻³ mol/L) of phenylephrine in the presence or absence of 100μmol/L of L-NAME. After completion of dose response to phenylephrine,potassium chloride (40 mmol/L) was added to ensure vessels couldcontract equally. Following constriction, the maximum diameter wasmeasured by incubating the vessel in a Krebs calcium free, ethyleneglycol tetraacetic acid (EGTA, 1 mmol/L) and sodium nitroprusside (10μmol/L) solution. Quantitation of vessel diameter was performed usingDMT vessel acquisition software and data are expressed as the percentageof initial diameter. Half maximal effective concentration (EC₅₀) andmaximum drug concentration (E_(max)) were calculated at previouslydescribed¹⁵.

Abdominal Aorta Ring Assay:

Abdominal aortas were isolated, cut into 2 mm wide rings and mounted ona DMT myograph system with low bath volumes as previously described¹⁶.Briefly, rings were stretched at 1.2× resting length in Krebs solutionand allowed to equilibrate for 30 min at 37° C. prior to depolarizationwith 154 mm K⁺ [i]. Following the high K⁺ contraction, rings werereturned to Krebs solution and incubated with 5 μmol/L Scr X or Hb α Xpeptide for 20 minutes. Cumulative concentrations of phenylephrine (PE)(10⁻¹⁰-10⁻⁴ mol/L) were added to the rings and the magnitude of thetension response measured in milli-newtons.

Blood Pressure Analysis:

Blood pressure was measured in conscious wildtype or eNOS^(−/−) miceunder unrestrained conditions using implanted radio telemetry units.Continuous blood pressure measurements were recorded using DataquestA.R.T. 20 software (DSI). To do so, mice were anesthetized withisoflurane and the catheters (TA11PA-C10, Data Sciences International(DSI)) were implanted in the left carotid artery. The catheter wastunneled through to the radiotransmitter, which was placed in asubcutaneous pouch along the flank. Mice were allowed to recover forseven days after surgery to regain normal circadian rhythms beforearterial pressure measurements and experiments were initiated. Thirtyminutes prior to peptide injection, continuous blood pressure readingswere recorded. Then, a bolus injection of Scr X or Hb α X peptide, orsaline was administered via an intraperitoneal injection at 0.125 mg/kg.One hour post-injection, blood pressure was recorded for a 30 minuteduration. The change in blood pressure was calculated by subtracting theaverage pre injection blood pressure from the average post-injectionblood pressure.

Statistics:

Statistics on individual comparisons were performed using Student'st-test. For multiple comparisons a one-way ANOVA was used and for doseresponse curves a two-way ANOVA followed by a Bonferroni's post-hoc testwas used. All statistics were computed using GraphPad Prism 5.

Results

Hb α X Peptide Disrupts the Interaction Between eNOS and Hb α.

Previous work demonstrated that eNOS and Hb α form a macromolecularcomplex and can directly interact⁹. Therefore, in silico modeling of theknown crystal structures for the oxygenase domain of eNOS and Hb α wasused to determine potential interactions based on geometric,electrostatic and hydrophobic indices. From this analysis, a discreet Hbα sequence (LSFPTTKTYFPHFDLSHGSA; SEQ ID NO:1) was found that interactedwith eNOS (FIG. 23). Sequences were subjected to homology analysis amongseveral mammalian species revealing a conserved peptide fragment (FIG.23). Therefore, a peptide (LSFPTTKTYF; SEQ ID NO:2) linked to an HIV tatsequence along with a scrambled control (FPYFSTKLTT; SEQ ID NO:40) weresynthesized. The peptides were named Hb α X and Scr X respectively.

To determine if these peptides competitively inhibited eNOS and Hb αbinding, Flag-eNOS was incubated with tat only, Scr X or Hb α X,followed by the addition of purified Hb α chains (FIG. 24a ). Complexeswere precipitated and subjected to Western blot analysis, demonstratingthat only Hb α X peptide significantly disrupted the eNOS/Hb αinteraction (FIG. 24b ). To test this ex vivo, thoracodorsal arterieswere incubated with peptides and measured colocalization of eNOS and Hbα on transverse sections using a proximity ligation assay (FIG. 25a ).These studies demonstrate decreased colocalization and a significantloss of protein-protein interaction between eNOS and Hb α (FIG. 25b ).Next, FITC-tagged Hb α X peptide was perfused into thoracodorsalarteries followed by fixation and immunolabeling for Hb α (FIG. 25c ),which resulted in marked colocalized FITC-tagged Hb α X peptide and Hb αin holes where MEJs are found (FIG. 25d ).

Hb α X Peptide Alters NO Signaling in the Vessel Wall.

Following α1_(D) adrenergic-mediated stimulation, it is known that NObinds to its receptor soluble guanylyl cyclase, resulting in increasedcGMP^(7-9,17). To determine the effects of Hb α X peptide on cGMPaccumulation during vasoconstriction, thoracodorsal arteries wereincubated with Scr X or Hb α X peptides and stimulated with the alpadrenergic agonist phenylephrine. A significant increase in cGMPaccumulation with Hb α X compared to the Scr X peptide was observed,which was reversed with the nitric oxide synthase inhibitor, L-NAME(FIG. 26a ). Previous work demonstrated that a monolayer of endothelialcells, in the absence of contact with smooth muscle cells, express verylittle Hb α⁹. Therefore, it was tested whether Scr X or Hb α X alteredbasal eNOS phosphorylation on serine 1177 (FIG. 27a ) or theaccumulation of the NO metabolite, nitrite (FIG. 27b ) in the culturemedium of human microvascular coronary endothelial cells. In theseexperiments, there were no differences in nitrite or eNOSphosphorylation. In addition, there was no change in nitriteaccumulation between Scr X and Hb α X treatments following stimulationof human microvascular coronary endothelial cells with bradykinin (FIG.27c ). The sum of these results indicates that the Hb α X peptideapplied ex vivo alters cGMP levels presumably by loss of interactionbetween Hb α and eNOS resulting in increase NO; however, the Hb α Xpeptide when applied to endothelial cells lacking protein expression ofHb α does not alter key components of eNOS metabolism.

Next, vasoreactivity was performed to determine the effect of thepeptide in response to phenylephrine. In thoracodorsal arteries,phenylephrine dose response curves with the Hb α X peptide revealed asignificant decrease in constriction compared to untreated arteries,which was reversed with L-NAME (FIG. 26b ). Differences are alsopresented as change in inner diameter measured in micrometers (FIG. 28a). The Scr X peptide showed no difference from control. Both the EC₅₀and E_(max) are shown in Table 7 and demonstrate a significantdifference only in the presence of Hb α X. The peptides did not alterbasal tone of the arteries (FIG. 28b ). Previous work has demonstratedthat conduit arteries (e.g. aorta, carotid) exhibit no Hb αexpression^(9, 18). Therefore, the effect of Hb α peptide on abdominalaortic arteries was investigated, which showed no significant change inphenylephrine dose response curves compared to untreated aortas oraortas treated with Scr X (FIG. 29). Lastly, because it has been shownabove that the Hb α X peptide disrupts Hb α/eNOS interaction, it wasproposed that eNOS^(−/−) mice should not have an altered phenotype whenHba X is applied. Indeed, when eNOS^(−/−) mice were treated with Hb α X,there was no alteration of the magnitude of phenylephrine inducedconstriction (FIG. 26c ). Together, these results demonstrate that theHb α X peptide induces significant changes in contractility due toincreased NO production that is confined to the small arteriesexpressing Hb α, but not in mice lacking eNOS or conduit arteries whereHb α is absent.

TABLE 7 E_(max) and EC₅₀ comparisons for vascular reactivity doseresponse curves. E_(max) is expressed as % initial diameter and EC₅₀ isthe [PE] producing half of the maximum effect, expressed in μmol/L.Control Hb α X Scr X Hbα X + L-NAME E_(max) 44.0 ± 7.6 68.0 ± 5.3 38.3 ±2.4 45.9 ± 3.0 EC₅₀  2.1 ± 0.8  6.8 ± 0.7  2.0 ± 1.3  1.9 ± 0.2

Hb α X Peptide Alters Systemic Blood Pressure.

The results above indicated the Hb α X peptide had a confined andsignificant effect on small artery NO release, but not conduit arteries.This provided initial evidence that the peptide could possibly alsoalter blood pressure regulation through a change in the peripheralresistance. Therefore, radio transmitters were implanted into C57Bl/6mice to elucidate the effect of Scr X or Hb α X peptide on systemicblood pressure changes. Administration of a single bolus of peptide(0.125 mg/kg) into C57BL/6 mice induced a significant decrease insystolic, diastolic and mean arterial blood pressure in mice injectedwith the Hb α X peptide, but not mice injected with saline or Scr Xpeptide (FIG. 30a ). The over or under expression of eNOS proteinsignificantly contributes to systemic blood pressure regulation¹⁹⁻²¹ andbecause of this it was tested whether Hba X could alter blood pressurein eNOS^(−/−) mice. Similar to the results with vasoreactivity, therewere no alterations in blood pressure in eNOS^(−/−) mice injected withsaline or either of the peptides (FIG. 30b ). Together, these resultsprovide in vivo evidence that the Hb α X peptide can alter bloodpressure homeostasis.

Discussion

Fluctuations in peripheral vascular resistance affecting blood pressurerequire regulation of blood vessel diameter through highly orchestratedcell signaling cascades and cell-cell communication events betweenendothelial and smooth muscle cells^(3, 4, 22-24). The known mechanismsregulating resistance arterial tone involve a multifaceted palate ofinputs including vasodilators such as endothelial derivedhyperpolarizing factor, prostaglandins and nitric oxide^(1, 2, 6). Therecent discovery of endothelial cell expressed Hb α as a key regulatorof NO diffusion to smooth muscle provides insight into how smallarteries regulate NO signaling during vasoconstriction⁹. The workpresented herein reveals several novel findings: (i) identification of aconserved sequence where eNOS and Hb α interface, (ii) development of anovel mimetic peptide inhibitor for disruption of eNOS/Hb αprotein-protein binding, (iii) identification of a novel mechanism bywhich coupling of eNOS/Hb α is used for NO scavenging and vascularreactivity, and (iv) the first line of evidence suggesting that theeNOS/Hb α interaction is used for blood pressure regulation. Theaggregate of these results offers new mechanistic insight by which Hb αregulates NO signaling in the vessel wall.

Based on previous work⁹, it was hypothesized that the strong associationand complex formation between Hb α and eNOS may be needed for thefunctional role of Hb α as a NO scavenger. The first step to test thishypothesis was to perform an in-depth protein-protein interactionanalysis using in silico modeling of the known crystal structures for Hbα and eNOS. One limitation to this analysis is that eNOS, comprised ofboth an oxygenase and reductase domain, only has the oxygenase domaincrystallized thereby constraining the modeling to this region. Despitethis restriction, a highly conserved Hb α sequence across multiplemammalian species was identified, which prompted the development ofmimetic peptides to this motif for competitive inhibitor studies.

Studies using purified Hb α and eNOS protein as well as ex vivo studieswith the peptide show greater that 90% inhibition of binding andassociation with the Hb X peptide, confirming the in silico modeling.Although this data does not identify where Hb α interacts with eNOS, itdoes provide direct evidence of a specific sequence of Hb α for bindingto eNOS.

Functionally, it was shown that Hb α X disrupts NO-dependent signalingas shown in cGMP and vasoreactivity studies. This work provides thefirst line of evidence demonstrating the importance of theprotein-protein interaction between Hb α and eNOS, possibly similar tothe mechanism by which caveolin-1 regulates eNOS³⁰⁻³². The possibilityof non-specific effects of Hb α X was ruled out assessed by basalphosphorylation of eNOS S1177, NO release measured by nitriteaccumulation in basal and stimulated conditions, the lack of effect inabdominal aortas (where Hb cc is not expressed) and in eNOS^(−/−)animals. Even though the functional effects of the peptide are apparent,it is still unclear at this point how the Hb α/eNOS complex assembles.The complex may be pre-constructed and assembled similar to that ofNADPH oxidase subunits³³. Based on previous work³⁰ and this study, it istempting to speculate that caveolin-1 maintains eNOS inactive untilstimulation, where eNOS then dissociates and recruits met-Hb α andpossibly cytochrome B5 reductase 3 to form a macromolecular complexallowing tight NO regulation.

Studies demonstrating an effect of the Hb α X peptide on blood pressureplaces the purified protein studies and in vitro and ex vivo experimentsinto a physiological context where NO signaling is significant.

Lastly, this discovery of a conserved Hb α sequence and the developmentof a novel Hb α mimetic inhibitor provide initial steps forunderstanding the basic physiological mechanisms that arterial bloodvessels use to regulate NO signaling. This work may provides a platformfor strategic development of small molecule inhibitors to treathypertension and possibly other related cardiovascular diseases.

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The disclosures of each and every patent, patent application, andpublication cited herein are hereby incorporated by reference herein intheir entirety.

Headings are included herein for reference and to aid in locatingcertain sections. These headings are not intended to limit the scope ofthe concepts described therein under, and these concepts may haveapplicability in other sections throughout the entire specification.

While this invention has been disclosed with reference to specificembodiments, it is apparent that other embodiments and variations ofthis invention may be devised by others skilled in the art withoutdeparting from the true spirit and scope of the invention.

What is claimed is:
 1. A peptide consisting of amino acid sequenceLSFPTTKTYFPHFDLSHGSA (SEQ ID NO:1) or a peptide consisting of amino acidsequence LSFPTTKTYF (SEQ ID NO:2), said peptide further comprising aplasma membrane permeability sequence.
 2. The peptide of claim 1,wherein the plasma membrane permeability sequence comprises an HIV-tattag sequence of YGRKKRRQRRR (SEQ ID NO:3).
 3. A pharmaceuticalcomposition comprising a peptide consisting of amino acid sequenceLSFPTTKTYFPHFDLSHGSA (SEQ ID NO:1) or a peptide consisting of amino acidsequence LSFPTTKTYF (SEQ ID NO:2), and a physiologically acceptablecarrier, wherein said amino acid sequence further comprises a plasmamembrane permeability sequence.
 4. The pharmaceutical composition ofclaim 3, wherein the plasma membrane permeability sequence comprises anHIV-tat tag sequence of YGRKKRRQRRR (SEQ ID NO:3).